drm: add an fb creation ioctl that takes a pixel format v5

To properly support the various plane formats supported by different
hardware, the kernel must know the pixel format of a framebuffer object.
So add a new ioctl taking a format argument corresponding to a fourcc
name from the new drm_fourcc.h header file.  Implement the fb creation
hooks in terms of the new mode_fb_cmd2 using helpers where the old
bpp/depth values are needed.

v2: create DRM specific fourcc header file for sharing with libdrm etc
v3: fix rebase failure and use DRM fourcc codes in intel_display.c and
    update commit message
v4: make fb_cmd2 handle field into an array for multi-object formats
    pull in Ville's fix for the memcpy in drm_plane_init
    apply Ville's cleanup to zero out fb_cmd2 arg in drm_mode_addfb
v5: add 'flags' field for interlaced support (from Ville)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Reviewed-by: Rob Clark <rob.clark@linaro.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>