ethtool: Fix link extended state for big endian

The link extended sub-states are assigned as enum that is an integer
size but read from a union as u8, this is working for small values on
little endian systems but for big endian this always give 0. Fix the
variable in the union to match the enum size.

Fixes: ecc31c60 ("ethtool: Add link extended state")
Signed-off-by: Moshe Tal <moshet@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -111,7 +111,7 @@ struct ethtool_link_ext_state_info {
 		enum ethtool_link_ext_substate_bad_signal_integrity bad_signal_integrity;
 		enum ethtool_link_ext_substate_cable_issue cable_issue;
 		enum ethtool_link_ext_substate_module module;
-		u8 __link_ext_substate;
+		u32 __link_ext_substate;
 	};
 };