drm: Add modeset object iterators

drm: Add modeset object iterators

And roll them out across drm_* files. The point here isn't code
prettification (it helps with that too) but that some of these lists
aren't static any more. And having macros will gives us a convenient
place to put locking checks into.

I didn't add an iterator for props since that's only used by a
list_for_each_entry_safe in the driver teardown code.

Search&replace was done with the below cocci spatch. Note that there's
a bunch more places that didn't match and which would need some manual
changes, but I've intentially left these out for this mostly automated
patch.

iterator name drm_for_each_crtc;
struct drm_crtc *crtc;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+ drm_for_each_crtc (crtc, dev) {
...
}

@@
iterator name drm_for_each_encoder;
struct drm_encoder *encoder;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+ drm_for_each_encoder (encoder, dev) {
...
}

@@
iterator name drm_for_each_fb;
struct drm_framebuffer *fb;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(fb, &dev->mode_config.fb_list, head) {
+ drm_for_each_fb (fb, dev) {
...
}

@@
iterator name drm_for_each_connector;
struct drm_connector *connector;
struct drm_device *dev;
expression head;
@@
- list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+ drm_for_each_connector (connector, dev) {
...
}

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>