mlxsw: spectrum_matchall: Convert if statements to a switch statement

Previous patch moved the protocol check out of the action check, so
these if statements can now be converted to a switch statement. Perform
the conversion.

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