drm: Add support for pps and compression mode command packet

After enabling DSC we need to send compression mode command packet
and pps data packet, for which 2 new data types are added
07h  Compression Mode Data Type Write , short write, 2 parameters
0Ah  PPS Long Write (word count determines number of bytes)
This patch adds support to send these packets.

Cc: David Airlie <airlied@linux.ie>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org

Changes in v3:
- None

Signed-off-by: vkorjani <vikas.korjani@intel.com>
[seanpaul removed pps_write_buffer fn, added types to packet_format helpers]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>