Add definitions for ADC channels for PMIC5 GEN3 ADC driver.
Add virtual channel definitions for PM5100, to be used
by ADC clients for PMIC5 GEN3.
Change-Id: I1180553c3ee697f994324c60ebfb4e996221108e
Signed-off-by: Jishnu Prakash <jprakash@codeaurora.org>