dwc3: gadget: restart timer on bus resume

Commit 80c2ae83 ("drivers: usb: dwc3: Remove xfer timer when going
to suspend") has dis-arm timer on bus suspend. Hence case where all
USB requests are queued at time of USB bus suspend and on resume there
is no request available to queue with USB controller, this timer is
not being re-arm. This results into temporarily data stall in UL as
controller is receiving sent data packets from host but software is
not receiving any completion on that bulk-out endpoint.

Also add macro to get bulk transfer timeout value in nanoseconds.

CRs-Fixed: 771888
Change-Id: I9f126b2ced15f3d7dcc93798c00c91f397a24302
Signed-off-by: Mayank Rana <mrana@codeaurora.org>