V4L/DVB (11141): em28xx: fix oops on ARM platform when allocating transfer buffers

Add missing URB_NO_TRANSFER_DMA_MAP flag, since	the use	of consistent memory
is not permitted for DMA on the ARM platform.

Thanks to Paul Thomas <pthomas8589@gmail.com> for providing sample ARM
hardware that was experiencing the oops (tested on the at91rm9200 based
LinuxStamp).

Thanks to David Brownell <david-b@pacbell.net> for providing insight into the
ARM memory architecture.

Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>