regulator: palmas: Correct TPS659038 register definition for REGEN2

The register offset for REGEN2_CTRL in different for TPS659038 chip as when
compared with other Palmas family PMICs. In the case of TPS659038 the wrong
offset pointed to PLLEN_CTRL and was causing a hang. Correcting the same.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org