mlxsw: spectrum: Allow driver to load with old firmware versions

The driver fails to load with old firmware versions that cannot report
the maximum number of RIF MAC profiles [1].

Fix this by defaulting to a maximum of a single profile in such
situations, as multiple profiles are not supported by old firmware
versions.

[1]
mlxsw_spectrum 0000:03:00.0: cannot register bus device
mlxsw_spectrum: probe of 0000:03:00.0 failed with error -5

Fixes: 1c375ff ("mlxsw: spectrum_router: Expose RIF MAC profiles to devlink resource")
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reported-by: Vadim Pasternak <vadimp@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -3290,10 +3290,10 @@ mlxsw_sp_resources_rif_mac_profile_register(struct mlxsw_core *mlxsw_core)
 	u8 max_rif_mac_profiles;
 
 	if (!MLXSW_CORE_RES_VALID(mlxsw_core, MAX_RIF_MAC_PROFILES))
-		return -EIO;
-
-	max_rif_mac_profiles = MLXSW_CORE_RES_GET(mlxsw_core,
-						  MAX_RIF_MAC_PROFILES);
+		max_rif_mac_profiles = 1;
+	else
+		max_rif_mac_profiles = MLXSW_CORE_RES_GET(mlxsw_core,
+							  MAX_RIF_MAC_PROFILES);
 	devlink_resource_size_params_init(&size_params, max_rif_mac_profiles,
 					  max_rif_mac_profiles, 1,
 					  DEVLINK_RESOURCE_UNIT_ENTRY);