dwc3: gadget: Don't queue USB request if pull up is getting disable

There is possible race as below:
a. pull up disable vs ep_queue() API
b. pull up disable vs kick transfer from completion context to queue
next request

pull up disable sends END transfer command to per endpoint, and give
back started request and pending request back to function driver.
dwc3_gadget_giveback() API does release spinlock which may allow
ep_queue() or completion handling to queue next request. This results
into TRB pending without invoking end transfer command, whereas request
is being given back to function driver and being freed. Hence on setting
next pull up enable, USB controller accesses previous stale TRB causing
unmapped page fault. Fix this issue by checking pull up disable or not
while handling ep_queue() or kicking any new transfer from other
transfer completion context.

Change-Id: I391aed05cbfe183cd3e2fe2f1aa335e4fd9ec37c
Signed-off-by: Mayank Rana <mrana@codeaurora.org>