regulator: tps62360: fix stylistic issue and optimize code

Fix multiple stylistic issue like:
- The print message should be not break into multiple line.
- line gap after variable declaration and statement.
- checkpatch error.
- some typo.

Some enhancement on error message printing to print error value
also along with proper text.

Avoid voltage_base conversion to microvolts every time.
Put init functions in init section.
Using efficient function inplace of calling multiple function
to reduce the code size.

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