fsl_usb2_udc: Remove check for udc == NULL in dr_controller_setup.

Remove check for udc == NULL in dr_controller_setup. All callers of
this function have already dereferenced udc at some point.

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>