usb: gadget: udc: renesas_usb3: remove redundant assignment to ret

Variable ret is being initialized with a value that is never read and
ret is being re-assigned immediately after the initialization in both
paths of an if statement. This is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>