power: qpnp-smbcharger: Add power-supply property for HVDCP 3.0 status

Use this property to determine if HVDCP3 is supported. HVDCP 3.0
is not supported at startup and needs to be enabled from
userspace. The charger is forced to 9V HVDCP 2.0 at all times
if HVDCP 3.0 is not enabled.

While at it remove the DT property 'qcom,enable-hvdcp-9v'.

Change-Id: I193bd959dd9cb5303f375d2720ec59914ef16032
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>