sfc: move initialisation of efx->filter_sem to efx_init_struct()

efx_probe_filters() has not been called yet when EF100 calls into
 efx_mcdi_filter_table_probe(), for which it wants to take the
 filter_sem.

Fixes: a9dc3d5 ("sfc_ef100: RX filter table management and related gubbins")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Link: https://lore.kernel.org/r/24fad43e-887d-051e-25e3-506f23f63abf@solarflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/sfc/efx_common.c

@@ -1014,6 +1014,7 @@ int efx_init_struct(struct efx_nic *efx,
 	efx->num_mac_stats = MC_CMD_MAC_NSTATS;
 	BUILD_BUG_ON(MC_CMD_MAC_NSTATS - 1 != MC_CMD_MAC_GENERATION_END);
 	mutex_init(&efx->mac_lock);
+	init_rwsem(&efx->filter_sem);
 #ifdef CONFIG_RFS_ACCEL
 	mutex_init(&efx->rps_mutex);
 	spin_lock_init(&efx->rps_hash_lock);

drivers/net/ethernet/sfc/rx_common.c

@@ -797,7 +797,6 @@ int efx_probe_filters(struct efx_nic *efx)
 {
 	int rc;
 
-	init_rwsem(&efx->filter_sem);
 	mutex_lock(&efx->mac_lock);
 	down_write(&efx->filter_sem);
 	rc = efx->type->filter_table_probe(efx);