staging: bcm2835-camera: Remove unused header

Remove the asm/cacheflush.h header include from mmal-vchiq.c. This
dependency was removed in:

commit 7e8dbea4 ("staging: bcm2835-camera: Remove explicit cache
flush operations")

Signed-off-by: Aymen Qader <qader.aymen@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>