usb: gadget: u_data_hsic: Use GFP_KERNEL where ever possible

The USB requests are allocated using dma pool API.  The dma pool has
limited memory for non-sleeping use case.  The current code does not
free USB requests during subsystem restart.  The requests are freed
only after cable is disconnected.  If subsystem restart happens
multiple  times without disconnecting cable, system may run out of the
dma pool memory.  This is leading to URB submission failures.  Use
GFP_KERNEL where ever possible.

CRs-Fixed: 463423
Change-Id: I0fca533e460e7b4234fe771e048e0e50494cb1da
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>