hwmon: pm8xxx_adc: Remove pm8921-adc

Switch clients to use pm8xxx-adc and remove pm8921-adc.
pm8xxx-adc supports PMIC HK/XOADC for 8960, 9x15, 8064
platforms.

Change-Id: Id27fa908cc097d52e6033c28ce243c6bcf64ed27
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
14 files changed