dwc3: gadget: Check for endpoint status before doing remote wakeup

If USB function driver is trying to queue USB request on endpoint,
we invoke remote wakeup functionality before queueing it if USB
device is already suspended. USB device is into suspended state
if USB cable is not being connected or USB is in bus suspend state.
With remote wakeup we are incrementing usb device's pm usage count
which is causing usb device not going into LPM later. Hence fix
this issue by checking endpoint enable status and if it is disable,
don't perform remote wakeup functionality.

CRs-Fixed: 723240
Change-Id: I70afec911f2ea05aeb787f8d5b0a6c2d0e517e2b
Signed-off-by: Mayank Rana <mrana@codeaurora.org>