In the future I want to allow tests to commit more properties,
but for this to work I have to fix all properties to work better
with atomic commit. Instead of special casing each
property make a bitmask for all property changed flags, and try to
commit all properties.

Changes since v1:
- Remove special dumping of src and crtc coordinates.
- Dump all modified coordinates.
Changes since v2:
- Move igt_plane_set_prop_changed up slightly.
Changes since v3:
- Fix wrong ordering of set_position in kms_plane_lowres causing a test failure.
Changes since v4:
- Back out resetting crtc position in igt_plane_set_fb() and
  document it during init. Tests appear to rely on it being preserved.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>