PMMP (Port Module Memory Map Properties) and MCION (Management Cable IO
and Notifications) registers are not supported on RJ45 ports, so setting
and getting power mode should be rejected.

Therefore, before trying to access those registers, validate the port
module type that was queried during initialization and return an error
to user space in case the port module type is RJ45 (twisted pair).

Set output example:

 # ethtool --set-module swp1 power-mode-policy auto
 netlink error: mlxsw_core: Power mode is not supported on port module type
 netlink error: Invalid argument

Get output example:

 $ ethtool --show-module swp11
 netlink error: mlxsw_core: Power mode is not supported on port module type
 netlink error: Invalid argument
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>