drm/i915: Add extra plane information in debugfs.

Extends i915_display_info so that for each active crtc also print
all planes associated with the pipe. This patch shows information
about each plane wrt format, size, position, rotation, and scaling.
This is very useful when debugging user space compositors that try
to utilize several planes for a commit.

V2: Fixed comments from Maarten, Ville, and Chris. Fixed printing of
16.16 fixpoint, better rotation bitmask management and some minor fixes

V3: Corrected state->src_x & 0x00ff to state->src_x & 0xffff...

Signed-off-by: Robert Fekete <robert.fekete@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445961512-25317-1-git-send-email-robert.fekete@linux.intel.com


Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>