staging: bcm2835-camera: Add multiple inclusion protection to headers

mmal-common.h and mmal-msg.h didn't have the normal
ifndef FOO / define FOO / endif protection to stop it being
included multiple times. Add it.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>