regmap: cache: Silence checkpatch warning

checkpatch.pl warned:
WARNING: ENOSYS means 'invalid syscall nr' and nothing else
Align the return value to regcache_drop_region().

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/20230313071812.13577-2-alexander.stein@ew.tq-group.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: tq-steina

drivers/base/regmap/regcache.c

@@ -242,7 +242,7 @@ int regcache_read(struct regmap *map,
 	int ret;
 
 	if (map->cache_type == REGCACHE_NONE)
-		return -ENOSYS;
+		return -EINVAL;
 
 	BUG_ON(!map->cache_ops);