[sonic-linkmgrd][master] submodule update (sonic-net#9904)

[sonic-linkmgrd][master] submodule update

ef1f5eb Jing Zhang Feb 3 09:37:25 2022 [linkmgrd] linkmgrd subscribes MUX_CABLE_INFO table to handle peer OIR events (#17)
bcd74b4 Jing Zhang Feb 1 09:52:00 2022 Collect ICMP packet loss information (#14)

sign-off: Jing Zhang zhangjing@microsoft.com