USB: gadget: Enable streaming mode support in hardware

Without streaming mode enabled, USB hardware fills Tx/Rx
buffers completely before starting a new transfer on USB
BUS. This helps to avoid underruns/overruns in bandwidth
limited systems. But, downside of using stream disable is
that it degrades USB throughput due to NYET handshake.

Since, MSM chips support high bandwidth over fabric, hence,
enable streaming mode to achieve better USB throughput.

Change-Id: I9a9e80c2c3061906ef24e60d6fb6626669ea19ce
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>