usb: gadget: f_qdss: Add support for mdm pcie channel

Driver needs to pass qdss data received from mdm qdss
bridge driver to host PC. This requires a software data
path using IN endpoint. Bridge driver needs to open
PCIE transport and use exported write() API to pass
the qdss data received from mdm. Driver calls the notify
call back upon write completion

Change-Id: I88f5fa1c1e9b94cc8c5253893371c1a85cb0e388
Signed-off-by: Pratham Pratap <prathampratap@codeaurora.org>