[Edgecore][AS7326]Modify sfputil to support python3

[jostar-yang]

Signed-off-by: jostar-yang jostar_yang@edge-core.com

Why I did it

Modify sfputil to support python3. Original code can work on python2, but it fail on python3

How I did it

1. Remove buffering=0 code. Add new open , read and write() code.
2. Remove buffer[0] = chr(regval) and use buffer[0]=reval.

How to verify it

Test sfputil cmd on 202012br image,

sfputil lpmode on Ethernet64

Enabling low-power mode for port Ethernet64... OK

sfputil show lpmode -p Ethernet64

Port Low-power Mode

---

Ethernet64 On

sfputil lpmode off Ethernet64

Disabling low-power mode for port Ethernet64... OK

sfputil show lpmode -p Ethernet64

Port Low-power Mode

---

Ethernet64 Off

root@as7326-56x-3:~# sfputil reset Ethernet72
Resetting port Ethernet72...
port_ps=/sys/bus/i2c/devices/18-0060/module_reset_55
reset:1
reset:0
OK

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
  -->The code base use python3
• 202106
  -->The code base use python3
• 202111
  -->The code base use python3
• 202205
  -->The code base use python3

Description for the changelog

Ensure to add label/tag for the feature raised. example - PR#2174 under sonic-utilities repo. where, Generic Config and Update feature has been labelled as GCU.

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)