mlxsw: cmd: Handle error after reset gracefully

There is an exception in command interface processing in case the MRSR
register is written to. The register triggers FW reset and during the
reset FW returns an error. So handle this by ignoring this error while
writing to MRSR register.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>