dwc3: gagdet: remove usage of PM runtime API with request handling

Currently code uses pm_runtime_get() to increment dwc3 usage count while
queueing USB request, and decrement same using pm_runtime_put() once
queued USB request is completed or aborted. Remove usage of these APIs
due to below reasons:
1. dwc3-msm is being parent device to dwc3. It makes sure not to allow
USB LPM until VBUS/ID notification. Also USB function driver (like ffs/
msc/bam/gsi) are incrementing dwc3 gadget device's PM usage count. So
incrementing and decrementing dwc3 device's PM usage count for each USB
request is little overkill.

2. ep_queue() API is not decrementing in case if it encounters any error
case before queueing USB request.

Change-Id: I6fbcdc4997cf65db3a4897136f1a06e7bf03eb82
Signed-off-by: Mayank Rana <mrana@codeaurora.org>