usb: gadget: f_gsi: Add QTI_CTRL_DATA_BUF_INFO ioctl

QTI needs to provide IN and OUT gsi endpoint request buffer length
and total size of the buffer length used by the driver to remote
subsystem. Hence add new ioctl to pass this information.

Change-Id: I4663a8f5f50c0888db142787e17852ebf6e64606
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>