hwmon: qpnp-adc-voltage: Add suspend_noirq support for VADC

With wakeup_source APIs in VADC driver if the client
driver suspend call requests adc conversion then
suspend process will be aborted even if the wakeup
event released by VADC driver.

Add suspend_noirq support to allow the client
driver to read adc during their suspend call
and remove wakeup_source APIs.

Change-Id: I338463975de0eafd9c9e21e5f0ce8a0508ceeac2
Signed-off-by: Dipen Parmar <dipenp@codeaurora.org>