[pfc] rectify asym pfc cli command by adding interface_name as parameter

[AmitKaushik7]

- What I did
Fixed the config interface pfc asymmetric CLI failure.

- How I did it
By adding the interface as a parameter to the CLI command( asymmetric command in config/main.py).

- How to verify it
By executing "sudo config interface pfc asymmetric <interface_name> on" command.

- Previous command output (if the output of a command-line utility has changed)
admin@sonic:~$ sudo config interface pfc asymmetric Ethernet9 on
Usage: config interface pfc asymmetric [OPTIONS] STATUS

Error: Invalid value for "status": invalid choice: Ethernet9. (choose from on, off)

- New command output (if the output of a command-line utility has changed)
admin@sonic:~$ sudo config interface pfc asymmetric Ethernet9 on

admin@sonic:~$

-->

[liat-grozovik]

please check #632 IMO it fixed the issues.

[jleveque]

Please resolve conflicts

[AmitKaushik7]

#632 addresses the issue partially. If any non-existing interface is used in this command, then the command succeeds and an invalid interface is added in the config DB which is incorrect.
Added an extra check(resolved the conflicts) in this script to apply it on valid physical interfaces only.

With this fix

admin@sonic:~$ sudo config interface pfc asymmetric Ethernet1111 on
Usage: config interface pfc asymmetric [OPTIONS] <interface_name> STATUS
Error: Interface name is invalid!!

With just #632

admin@sonic:$ sudo config interface pfc asymmetric Ethernet1111 on
admin@sonic:$ show int sta
Interface Lanes Speed MTU Alias Vlan Oper Admin Type Asym PFC

---

Ethernet0 49,50,51,52 100G 9100 hundredGigE1 routed down down N/A on
Ethernet4 53,54,55,56 100G 1710 hundredGigE2 routed down down QSFP+ or later on
......
......
Ethernet92 29,30,31,32 100G 9100 hundredGigE24 routed down down N/A N/A
Ethernet96 113,114,115,116 100G 9100 hundredGigE25 routed down down N/A N/A
Ethernet100 117,118,119,120 100G 9100 hundredGigE26 routed down down N/A N/A
Ethernet104 121,122,123,124 100G 9100 hundredGigE27 routed down down N/A N/A
Ethernet108 125,126,127,128 100G 9100 hundredGigE28 routed down down N/A N/A
Ethernet112 1,2,3,4 100G 9100 hundredGigE29 routed down down N/A N/A
Ethernet116 5,6,7,8 100G 9100 hundredGigE30 routed down down N/A N/A
Ethernet120 9,10,11,12 100G 9100 hundredGigE31 routed down down N/A N/A
Ethernet124 13,14,15,16 100G 9100 hundredGigE32 routed down down N/A N/A
Ethernet1111 N/A N/A N/A N/A routed N/A N/A N/A on <==== New Entry(Ethernet1111) in the ConfigDB