regmap: Fix regmap_bulk_write single-rw mutex deadlock

When regmap_bulk_write() is called with the map->use_single_rw flag set
an immediate mutex deadlock happens because regmap_raw_write() is called
after obtaining the mutex and regmap_raw_write() itself then tries to
obtain the mutex as well.

It is obvious that no one other than myself tried it with a real device.
I did, but only for the purposes of an experiment and demonstration.

But even if this situation will never ever happen with a real device, it
is a bug and therefore should be fixed.

Signed-off-by: Anthony Olech <anthony.olech.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/regmap.c

@@ -1418,10 +1418,11 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 	 */
 	if (map->use_single_rw) {
 		for (i = 0; i < val_count; i++) {
-			ret = regmap_raw_write(map,
-					       reg + (i * map->reg_stride),
-					       val + (i * val_bytes),
-					       val_bytes);
+			ret = _regmap_raw_write(map,
+						reg + (i * map->reg_stride),
+						val + (i * val_bytes),
+						val_bytes,
+						false);
 			if (ret != 0)
 				return ret;
 		}