regulator: core: Fix kerneldoc comments

Remove the description for the non-existing 'ret' to fix the build warning:
./drivers/regulator/core.c:1467: warning:
Excess function parameter 'ret' description in 'regulator_dev_lookup'.
The description found for the return value is: @ret: 0 on success, -ENODEV
if lookup fails permanently, -EPROBE_DEFER if lookup could succeed in the future.

Signed-off-by: Tamara Diaconita <diaconita.tamara@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1451,8 +1451,6 @@ static struct regulator_dev *regulator_lookup_by_name(const char *name)
  * regulator_dev_lookup - lookup a regulator device.
  * @dev: device for regulator "consumer".
  * @supply: Supply name or regulator ID.
- * @ret: 0 on success, -ENODEV if lookup fails permanently, -EPROBE_DEFER if
- * lookup could succeed in the future.
  *
  * If successful, returns a struct regulator_dev that corresponds to the name
  * @supply and with the embedded struct device refcount incremented by one.