regulator: palmas: Slightly code change for better readability

It's a little bit hard to read that the "else" case means id == PALMAS_REG_SMPS10.

if (id != PALMAS_REG_SMPS10){
        do something for the cases id != PALMAS_REG_SMPS10;
} else {
        do something for the case id == PALMAS_REG_SMPS10;
}

This patch changes above syntax to switch statement.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>