platform: qpnp-power-on: choose correct s2 control registers

The PMICs which have PON_REVISION2 register value as 0x00
have a single register for both s2 reset type and
s2 reset enable. All the other PON revisions have separate
registers for s2 reset type and s2 reset enable. Add support
to choose correct s2 control registers based on PON_REVISION2
register value.

Change-Id: Iaf0fb5c10a6883092d6a49336c40df0db7940ad2
CRs-Fixed: 661934
Signed-off-by: Abinaya P <abinayap@codeaurora.org>