regulator: tps65217: Convert to set_voltage_sel and map_voltage

Convert tps65217_pmic_ops to use set_voltage_sel and map_voltage.
After this convertion, we can also use tps65217_pmic_set_voltage_sel()
for set_voltage_sel callback of tps65217_pmic_ldo1_ops.
Thus this patch also removes tps65217_pmic_ldo1_set_voltage_sel() function.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>