regulator: sc2731: Fix defines for SC2731_WR_UNLOCK and SC2731_PWR_WR_PROT_VALUE

The defines for SC2731_WR_UNLOCK and SC2731_PWR_WR_PROT_VALUE makes
regmap_write() call looks strange because it takes reg parameter fist
then val.
Base on Erick's suggestion to define SC2731_PWR_WR_PROT and
SC2731_WR_UNLOCK_VALUE instead.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Erick Chen <erick.chen@spreadtrum.com>
Signed-off-by: Mark Brown <broonie@kernel.org>