regmap: cache: Return error in cache sync operations for REGCACHE_NONE

There is no sense in doing a cache sync on REGCACHE_NONE regmaps.
Instead of panicking the kernel due to missing cache_ops, return an error
to client driver.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/20230313071812.13577-1-alexander.stein@ew.tq-group.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: tq-steina

drivers/base/regmap/regcache.c

@@ -349,6 +349,9 @@ int regcache_sync(struct regmap *map)
 	const char *name;
 	bool bypass;
 
+	if (WARN_ON(map->cache_type == REGCACHE_NONE))
+		return -EINVAL;
+
 	BUG_ON(!map->cache_ops);
 
 	map->lock(map->lock_arg);
@@ -418,6 +421,9 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
 	const char *name;
 	bool bypass;
 
+	if (WARN_ON(map->cache_type == REGCACHE_NONE))
+		return -EINVAL;
+
 	BUG_ON(!map->cache_ops);
 
 	map->lock(map->lock_arg);