usb: phy-msm-usb: Fix reporting of POWER_SUPPLY_PROP_PRESENT

Currently when querying the usb power_supply property for PROP_PRESENT
it returns the value given by PROP_ONLINE, which indicates whether
the USB peripheral has enumerated or not. This is incorrect and should
instead reflect the state of the USB cable connection (VBUS indication)
irrespective of enumeration state.

Change-Id: I8292cbad36fd4a88e97d97f0c350a21d924bca10
Signed-off-by: Jack Pham <jackp@codeaurora.org>