regmap: rbtree: Fix register default look-up in sync

The code currently passes the register offset in the current block to
regcache_lookup_reg. This works fine as long as there is only one block and with
base register of 0, but in all other cases it will look-up the default for a
wrong register, which can cause unnecessary register writes. This patch fixes
it by passing the actual register number to regcache_lookup_reg.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: <stable@vger.kernel.org>

drivers/base/regmap/regcache-rbtree.c

@@ -396,7 +396,7 @@ static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
 							   map->cache_word_size);
 
 			/* Is this the hardware default?  If so skip. */
-			ret = regcache_lookup_reg(map, i);
+			ret = regcache_lookup_reg(map, regtmp);
 			if (ret >= 0 && val == map->reg_defaults[ret].def)
 				continue;