[media] media: platform: pxa_camera: trivial move of functions

Move the functions in the file to be regrouped into meaningful blocks :
 1. pxa camera core handling functions, manipulating the herdware
 2. videobuf2 functions, dealing with video buffers
 3. video ioctl (vidioc) related functions
 4. driver probing, removal, suspend and resume

This patch doesn't modify a single line of code.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>