msm: qpnp-power-on: Add QPNP PMIC power-on(PON) driver

The power-on module of the PMIC provides support for
power-key, reset and power on/off reasons and other
power-on related functionality.
The driver currently supports only the power-key detection.

Change-Id: If7d42ce38fba6e9a590d0953daadcd43ab746112
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>