V4L/DVB (3376): Add cpia2 camera support

There has been a CPIA2 driver out of kernel for a long time and it has
been pretty clean for some time too. This is an import of the
sourceforge driver which has been stripped of
- 2.4 back compatibility
- 2.4 old style MJPEG ioctls
A couple of functions have been made static and the docs have been
repackaged into Documentation/video4linux.  The rvmalloc/free functions now
match the cpia driver again.  Other than that this is the code as is.
Tested on x86-64 with a QX5 microscope.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>