staging: vc04_services: bcm2835-camera: avoid the use of typedef for function pointers

Replace typedef bm2835_mmal_v4l2_ctrl_cb with equivalent declaration to
better align with the linux kernel coding style.

Signed-off-by: Gaston Gonzalez <gascoar@gmail.com>
Link: https://lore.kernel.org/r/0418e6e19e1580fff4abfc4bb2f4269dc206df44.1640776340.git.gascoar@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>