usb: dwc3: otg: Avoid unbalanced runtime PM

In dwc3_ext_event_notify() the pm_runtime_status_suspended()
call will only check the momentary status of the device, but
does not consider that it could be currently active and may
be in the middle of or will soon enter a suspended state.
In those cases, it would skip an important call to
pm_runtime_get(), leaving the usage_counter as 0, the result
of which could allow a suspend to trigger prematurely after
kicking the OTG state machine. If the controller's suspend
routine is completed while later execution assumes the device
is not suspended, the system may crash due to invalid unclocked
register access.

Further, a pm_runtime_put() from otg_sm_work may even exacerbate
by allowing the usage_counter to go below 0. The previous
commit 48263195 "usb: dwc3: otg: Prevent negative runtime PM
count in host mode" tried to fix this by using
pm_runtime_put_noidle() to keep from going past 0, but that
is only a band-aid.

Fix this by checking not just runtime_status but also the current
usage_counter. If it's 0, it surely needs to be incremented with
the subsequent pm_runtime_get() call. The exit points from the
state machine function that allow suspend will then call
pm_runtime_put() which would be balanced.

Change-Id: Iffe83f022a9128dcb846f2acb26d510f1c611eea
Signed-off-by: Jack Pham <jackp@codeaurora.org>