power: qpnp-smbcharger: correctly detect 9V chargers

Currently the charger driver is incorrectly using the INPUT_STS register
to detect 9V charging for parallel charging. This register will show
5V-9V charger for both normal and HVDCP chargers, causing parallel
charging to also not start for HVDCP chargers when input current limit
is under 1.4A.

Fix this by using the USBIN_HVDCP_STS register instead. This will
correctly detect 9V HVDCP operation and allow parallel charging to start
at 700mA when using a 9V charger.

CRs-Fixed: 733213
Change-Id: I21fdfd3b400b5000fa91f794157024b0bea49e57
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>