ARM: bcm2835_defconfig: Enable BCM2835 MMAL-based V4L2 camera driver

This enables the bcm2835-camera driver, which depends on bcm2835-vchiq.
After that we gain more test coverage (e.g. Kernel CI).

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>