fotg210-udc: Remove unneeded variable

This patch fixes below warning reported by coccicheck

drivers/usb/gadget/udc/fotg210-udc.c:484:5-8: Unneeded variable: "ret".
Return "0" on line 507

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>