dwc3-msm: reset hardware on bootup if cable not connected

commit b8177195 ("usb: dwc3: Start the core in host mode only if
there is no extcon") removed starting usb state machine from probe which
will reset controller/phy and put them in low power mode. Without it,
HW will be in POR state which might not be optimal low power state.
Also, check for dpdm regulator status before starting state machine
as it might interfere with apsd (automatic power source detection).

Change-Id: I178ec1e115a79ee19a1c43c74f01dd72c8b12a4b
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>