hwmon: epm_adc: Add psoc voltage scaling
hwmon: epm_adc: Add psoc voltage scaling

For voltage channels the psoc uses a 12 bit ADC. For current
channels a 16 bit ADC is used with the sign bit. Use the
channel mask to determine the channel scaling being performed
is for a voltage channel and scale the result appropriately
for voltage and current channel.

Change-Id: I7e238dd6ed0de6bcfaaf4186eaa3770de43d254f
Signed-off-by: Siddartha Mohanadoss <9c97603a3a6be1a8a5dd7a9c9672e79ad0487bf3@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas