acctonbmc: Fix oob-mdio-util.sh write operation

[louis-nexthop]

Description

Fix bug in the write operation of oob-mdio-util.sh.

1. data is the forth argument, not the third.
2. ctrl_cmd must be in hex representation because mdio-util expects it here. So, I used printf "0x%08X", similar to how it's done for the read operation.

Motivation

oob-mdio-util.sh has a bug when doing a register write to the OOB management switch.

Test Plan

Before:
Note: usage is oob-mdio-util.sh {read|write} <port> <offset> [<value>]

root@bmc-oob:~# oob-mdio-util.sh read 1 0x7
Write to PHY 0x12.0x0, value is 0x9a27
Read from PHY 0x12.0x1, value is 0x1         # <----- Read: got 0x1

root@bmc-oob:~# oob-mdio-util.sh write 1 0x7 0xabcd
Write to PHY 0x12.0x1, value is 0x7
Write to PHY 0x12.0x0, value is 0x38439      # <----- Write: wrong command was sent. ctrl_cmd supposed to be a 16-bit value

root@bmc-oob:~# oob-mdio-util.sh read 1 0x7
Write to PHY 0x12.0x0, value is 0x9a27
Read from PHY 0x12.0x1, value is 0x1         # <----- Read back: WRONG! Still got 0x1

After:

root@bmc-oob:~# oob-mdio-util.sh read 1 0x7
Write to PHY 0x12.0x0, value is 0x9a27
Read from PHY 0x12.0x1, value is 0x1

root@bmc-oob:~# oob-mdio-util.sh write 1 0x7 0xabcd
Write to PHY 0x12.0x1, value is 0xabcd
Write to PHY 0x12.0x0, value is 0x9627        # <----- Write: correct value of ctrl_cmd

root@bmc-oob:~# oob-mdio-util.sh read 1 0x7
Write to PHY 0x12.0x0, value is 0x9a27
Read from PHY 0x12.0x1, value is 0xabcd       # <----- Read back: GOOD! Got the value we wrote

[meta-codesync]

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