regcache: Mark cache dirty if selector register rewrite fails

After a successful cache synchronization, regcache_sync() clears
cache_dirty. If rewriting a selector register later fails, the cache
and hardware become inconsistent while the cache still appears clean.

Update cache_dirty to reflect the cache and hardware state when
selector register rewriting fails.

Signed-off-by: bui duc phuc <phucduc.bui@gmail.com>
Link: https://patch.msgid.link/20260713050312.38729-3-phucduc.bui@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: BuiDucPhuc

drivers/base/regmap/regcache.c

@@ -465,6 +465,7 @@ int regcache_sync(struct regmap *map)
 
 		selector_ret = _regmap_write(map, this->selector_reg, i);
 		if (selector_ret != 0) {
+			map->cache_dirty = true;
 			dev_err(map->dev, "Failed to write %x = %x: %d\n",
 				this->selector_reg, i, selector_ret);
 			break;