[Mellanox] [202012] Update SAI submodule pointer (#7499)

- Why I did it
To include below changes:
Set monitoring VLAN hostif up dy default (for VNET ping tool)

- How I did it
Updated SAI submodule pointer

- How to verify it
Create VLAN hostif according to changes in PR: sonic-net/sonic-swss#1645
Verify it is admin up by default

Signed-off-by: Volodymyr Samotiy <[email protected]>

Author: volodymyrsamotiy