cx88-video build fix

cx88-video build fix

alpha:

drivers/media/video/cx88/cx88-video.c: In function 'cx8800_initdev':
drivers/media/video/cx88/cx88-video.c:1782: error: 'DMA_32BIT_MASK' undeclared (first use in this function)
drivers/media/video/cx88/cx88-video.c:1782: error: (Each undeclared identifier is reported only once
drivers/media/video/cx88/cx88-video.c:1782: error: for each function it appears in.)

Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>