regmap: Allow users to query the size of register values

Generic infrastructure based on top of regmap may want to operate on
blocks of data and therefore find it useful to find the size of the
register values. Provide an accessor operation for this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index eb93921..089479f 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -143,6 +143,7 @@
 int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 			     unsigned int mask, unsigned int val,
 			     bool *change);
+int regmap_get_val_bytes(struct regmap *map);
 
 int regcache_sync(struct regmap *map);
 void regcache_cache_only(struct regmap *map, bool enable);