fsl_usb2_udc: Make fsl_queue_td return type void.

fsl_queue_td always returns 0. Make it void and remove checks for non-zero
return in callers.

Signed-off-by: Will Newton <will.newton@gmail.com>
Acked-by: Li Yang <leoli@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>