Fix nodepool reconciliation issue

[shyamradhakrishnan]

What this PR does / why we need it:
Fix nodepool reconciliation issue when there are no NSGs

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[shyamradhakrishnan]

e2e

Ran 7 of 28 Specs in 3159.913 seconds
SUCCESS! -- 7 Passed | 0 Failed | 0 Pending | 21 Skipped

[shyamradhakrishnan]

unit test

?   	github.com/oracle/cluster-api-provider-oci	[no test files]
ok  	github.com/oracle/cluster-api-provider-oci/api/v1beta1	56.069s	coverage: 23.7% of statements
ok  	github.com/oracle/cluster-api-provider-oci/api/v1beta2	0.044s	coverage: 15.6% of statements
?   	github.com/oracle/cluster-api-provider-oci/cloud/config	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/metrics	[no test files]
ok  	github.com/oracle/cluster-api-provider-oci/cloud/ociutil	0.006s	coverage: 19.6% of statements
ok  	github.com/oracle/cluster-api-provider-oci/cloud/scope	242.185s	coverage: 75.1% of statements
?   	github.com/oracle/cluster-api-provider-oci/cloud/scope/mocks	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/base	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/base/mock_base	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/compute	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/compute/mock_compute	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/computemanagement	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/computemanagement/mock_computemanagement	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/containerengine	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/containerengine/mock_containerengine	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/identity	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/identity/mock_identity	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/loadbalancer	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/loadbalancer/mock_lb	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer/mock_nlb	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/vcn	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/vcn/mock_vcn	[no test files]
ok  	github.com/oracle/cluster-api-provider-oci/cloud/util	0.087s	coverage: 73.4% of statements
ok  	github.com/oracle/cluster-api-provider-oci/controllers	26.872s	coverage: 57.9% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/api/v1beta1	13.690s	coverage: 15.2% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/api/v1beta2	0.015s	coverage: 4.8% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/controllers	0.383s	coverage: 56.0% of statements
?   	github.com/oracle/cluster-api-provider-oci/feature	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/version	[no test files]