usb: gadget: f_gsi: Notify line state change from set_alt for RmNet

Currently the driver notifies line state change to QTI for RmNet
interface on getting the line state SET control request from the
host. There is a requirement now that the QTI wants to query IPA
for ep_info once the data path has been set up. Hence, send the
zero byte packet for line state change from setup() function to
set_alt after the xdci_connect has been done. QTI can then query
USB and IPA for info via IOCTLs.

Change-Id: Iecae2c7e67b63474d26fcbccada9ebe2364295a7
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>