regmap: Mark the cache as clean after a successful sync

Previously the cache would never be marked clean, meaning syncs would
never be suppressed which isn't the end of the world but could be
inefficient.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 4d43ed3..46c42d3 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -285,6 +285,9 @@
 
 	ret = map->cache_ops->sync(map);
 
+	if (ret == 0)
+		map->cache_dirty = false;
+
 out:
 	trace_regcache_sync(map->dev, name, "stop");
 	/* Restore the bypass state */