[gbsyncd] Enable debug shell for BRCM broncos PHY

[jimmyzhai]

Why I did it

In docker-gbsyncd-broncos image, enable debug shell support for BRCM broncos PHY.

How I did it

How to verify it

Note: need enable attr SAI_SWITCH_ATTR_SWITCH_SHELL_ENABLE support in BCM PAI library

# bcmsh 
Press Enter to show prompt.
Press Ctrl+C to exit.
NOTICE: Only one bcmsh or bcmcmd can connect to the shell at same time.


BRCM:> help
help
List of available commands
- h or help => Print command menu
- l => Print list of active ports on the PHY
- ps <port_id> <options> =>  Print port status
  <options> =>  1 -> Link status
            =>  2 -> Link training failure status
            =>  3 -> Link training RX status
            =>  4 -> PRBS lock status
            =>  5 -> PRBS lock loss status
- rd <port_id> <addr> <no of registers to read> => Read register contents
- wr <port_id> <addr> <data> => Write register data
- rrd <lanemap> <if_side> <addr> <no of registers to read> => Raw read register contents using lanemap and if_side (line = 0, system = 1)
- rwr <lanemap> <if_side> <addr> <data> => Raw write register data using lanemap and if_side (line = 0, system = 1)
- fw or firmware => Print firmware version of the PHY
- pd or port_dump <port_id> <flags> => Dump port status
- eyescan <port_id> => Display eye scan 
- fec_status <port_id> => Get fec status of the port
- polarity <lanemap> <if_side> <TX polarity> <RX Polarity> => Set TX and RX polarity
    <lanemap> => 0xF, 0xFF, or 0xFFFF based on number of lanes
    <if_side > => Line = 0, System = 1
    <TX/RX Polarity> =>_TX/RX Polarity bitmap of all lanes
        Each bit represents a lane number.
        E.g. Lane 0's polarity value (0 or 1) is populated in Bit 0.
- polarity <lanemap> <if_side> => Print TX and RX polarity
- lb <port_id> <lb_value> => Enable loopback on the port
  lb_value = 0 -> Disable, 1 -> PHY, 2 -> MAC
- lb <port_id> => Print loopback configuration of the port
- prbs <port_id> <options> <val> => Set/Get PRBS configuration
  <options> => 1 -> Get PRBS state and polynomial
               2 -> Set PRBS Polynomial, <val> - PRBS Polynomial
                    Please refer to phy/chip documentation for valid values
               3 -> Enable PRBS
                    <val> => 0 Disable PRBS
                             1 Enable both PRBS Transmitter and Receiver
                             2 Enable PRBS Receiver
                             3 Enable PRBS Transmitter
  exit or q => Exit the diagnostic shell

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

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205

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)