regulator: core: Don't corrupt display when printing uV offsets

We weren't taking into account the already used buffer when telling
sprintf() where to print to.

Reported-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -801,7 +801,7 @@ static void print_constraints(struct regulator_dev *rdev)
 	}
 
 	if (constraints->uV_offset)
-		count += sprintf(buf, "%dmV offset ",
+		count += sprintf(buf + count, "%dmV offset ",
 				 constraints->uV_offset / 1000);
 
 	if (constraints->min_uA && constraints->max_uA) {