usb: gadget: Add new ipc log buffer to log request and dma

Add new IPC log buffer to log the events in the cycle
of requests like queue, mapping the associated buffer,
unmapping it and finally dequeuing it.
This logging will help us in debugging the SMMU faults
for which the traces has to be enabled. These logs
helps to trace the faulty address in the first incident.

The logs can be accessed on the target using the command
echo 0 > /proc/sys/kernel/kptr_restrict
cat /sys/kernel/debug/ipc_logging/a600000.dwc3.ep_events/log.

Change-Id: Icc7063da7a251902cbb257022eaff6656e972a07
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>