msm_otg: hack to allow automatic usb host mode (externally powered)

Force ID_A (host mode + charging) on detection of proprietary charger (Apple-compatible charger with voltage on D+/D-).
Unforce ID_A on PMIC: BSV clear (detection of loss of charger).
Use charger type ACA_DOCK and allow up to 1.5A charge rate in host mode.
msm_otg: hack to allow manual usb host mode (externally powered) Part_2

Enable debugfs /sys/kernel/debug/msm_otg/mode for manual otg mode manipulation.
Always force requested mode (none, peripheral, host).
Use ID_A bit instead of ID for host mode.

Note: There are no provisions for charger detection when setting host mode manually.