platform: qpnp-power-on: Update the PON subtype check

Update the PON subtypes as below
PON_PRIMARY, PON_SECONDARY - GEN1 subtype
PON_GEN2_PRIMARY, PON_GEN2_SECONDARY - GEN2 subtype

Also, add a new subtype PON_1REG which uses the
register offsets of GEN_V2.

Change-Id: I9e56f3129af60f6b68e11e51e8c96ab57c025b3f
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>