msm: qpnp-power-on: Add reset configuration support

The PON module supports various reset sources (physical pins)
such as KPDPWR, RESIN, RESIN+KPDPWR. These pins can be configured
for different reset types (such as warm, soft, hard) and can also
be used as push buttons (keys).

In the push-button configuration these pins act as gpios, only
reporting the state on the line (high/low) and no additional
pon based configuration being done in the hardware or software.
They can be used for generic buttons (such as volume up/down,
directional keys)

Change-Id: Icde78b49b1037c1b5a13d7e90f772f72ac822b2a
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>