hwmon: (pmbus) Remove trailing whitespaces from Kconfig file

Fix checkpatch issues by removing trailing whitespaces in Kconfig.
Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
Link: https://lore.kernel.org/r/c984b88b136a1cde16ce52c5f818886653b0f84a.1642434222.git.sylv@sylv.io
[groeck: Updated subject]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>