msm: qpnp-usbdetect: Report initial VBUS state on bootup

Interrupt for Vbus detection may not be fired if system boots up
with USB cable connected or Vbus HIGH. Read Vbus state on bootup
and call power_supply API explicitly to report Vbus state.

Change-Id: Ic5b4fd6ba495e7bd7c78de4a7e0ac68e851b4cc4
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>