sfc/siena: Use the bitmap API to allocate bitmaps

Use bitmap_zalloc()/bitmap_free() instead of hand-writing them.

It is less verbose and it improves the semantic.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://lore.kernel.org/r/717ba530215f4d7ce9fedcc73d98dba1f70d7f71.1657049636.git.christophe.jaillet@wanadoo.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/sfc/siena/farch.c

@@ -2778,7 +2778,7 @@ void efx_farch_filter_table_remove(struct efx_nic *efx)
 	enum efx_farch_filter_table_id table_id;
 
 	for (table_id = 0; table_id < EFX_FARCH_FILTER_TABLE_COUNT; table_id++) {
-		kfree(state->table[table_id].used_bitmap);
+		bitmap_free(state->table[table_id].used_bitmap);
 		vfree(state->table[table_id].spec);
 	}
 	kfree(state);
@@ -2822,9 +2822,7 @@ int efx_farch_filter_table_probe(struct efx_nic *efx)
 		table = &state->table[table_id];
 		if (table->size == 0)
 			continue;
-		table->used_bitmap = kcalloc(BITS_TO_LONGS(table->size),
-					     sizeof(unsigned long),
-					     GFP_KERNEL);
+		table->used_bitmap = bitmap_zalloc(table->size, GFP_KERNEL);
 		if (!table->used_bitmap)
 			goto fail;
 		table->spec = vzalloc(array_size(sizeof(*table->spec),