usb: gsi: Capture USB GSI endpoint operations

In some cases it has been observed that after sending STARTXFER
command with USB GSI IN endpoint, USB controller is accessing zero
address resulting into bus error. This change captures USB GSI
operation sequence in debug buffer which may help to understand
race condition in terms of USB gadget events and USB GSI endpoint
operations.

Change-Id: Ia46877bb92ea0cc1d5f3712e5c70bb44232d5cfe
Signed-off-by: Mayank Rana <mrana@codeaurora.org>