Fix panic in TestVlansAndBonds

[milan-zededa]

I have accidentaly added duplicate call to release() in TestVlansAndBonds as part of my recently merged PR.

This can trigger panic:

goroutine 52 [running]:
sync.fatal({0x17540dd?, 0xffffffff?})
	/usr/lib/go/src/runtime/panic.go:1031 +0x1e
sync.(*Mutex).unlockSlow(0xc0004bee00, 0xffffffff)
	/usr/lib/go/src/sync/mutex.go:229 +0x49
sync.(*Mutex).Unlock(0xc0004bee00)
	/usr/lib/go/src/sync/mutex.go:223 +0x55
github.com/lf-edge/eve/pkg/pillar/dpcreconciler.(*LinuxDpcReconciler).pauseWatcher.func1()
	/pillar/dpcreconciler/linux.go:272 +0x73
github.com/lf-edge/eve/pkg/pillar/dpcreconciler_test.TestVlansAndBonds(0xc00009ba00?)
	/pillar/dpcreconciler/linux_test.go:915 +0x2c16
testing.tRunner(0xc00009ba00, 0x17a82b8)
	/usr/lib/go/src/testing/testing.go:1576 +0x217
created by testing.(*T).Run
	/usr/lib/go/src/testing/testing.go:1629 +0x806