Usually, when usb is gone, usb_usage_count is 1 and and msm_sm_work function will release msm_otg lock.
Howerverer, when pugin and unplugin usb quickly, usb_usage_count may be not released by charger detection work and is larger than 1.
It will prevent system from sleeping. So fix usb_usage_count to 1 when unplugin the charger.

Change-Id: I00f4e1b57f7229c537cee4a7107edc129af4e9da