usb: f_gsi: Increase ADPL buffer depth to 30

During high embedded throughput workloads having ADPL enabled
may impact performance as it becomes a bottleneck for IPA if
log packets are not drained quickly enough. To alleviate this,
increase the number of buffers allocated for the ADPL GSI pipe
to 30 allow for the USB host to consume log packets from the
ADPL endpoint as fast as possible.

Change-Id: I33102608367e71a4e75837f8d2a396f20f386b7a
Signed-off-by: Jack Pham <jackp@codeaurora.org>