regulator: palmas: Update the DT binding doc for smps10 out1 and out2

Palmas regulator SMPS10 is splitted into two regulators SMPS10-OUT1 and
SMPS10-OUT2 to match with hw behavior. With this regulator's name got
changed in driver.

Update the DT binding document to match with driver.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>