usb: gadget: factor out alloc_ep_req

alloc_ep_req() is a function repeated in several modules.
Make a common implementation and use it.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --cc drivers/usb/gadget/Makefile
Simple merge

diff --cc drivers/usb/gadget/f_hid.c
Simple merge

diff --cc drivers/usb/gadget/f_loopback.c
Simple merge

diff --cc drivers/usb/gadget/f_midi.c
Simple merge

diff --cc drivers/usb/gadget/f_sourcesink.c
Simple merge

diff --cc drivers/usb/gadget/g_zero.h
Simple merge

diff --cc drivers/usb/gadget/u_f.c
Simple merge

diff --cc drivers/usb/gadget/u_f.h
Simple merge