drm/dsc: Define VESA Display Stream Compression Capabilities

This defines all the DSC parameters as per the VESA DSC spec
that will be required for DSC encoder/decoder

v6: (From Manasi)
* Add a bit mask for RANGE_BPG_OFFSET for 6 bits(Manasi)
v5 (From Manasi)
* Add the RC constants as per the spec
v4 (From Manasi)
* Add the DSC_MUX_WORD_SIZE constants (Manasi)

v3 (From Manasi)
* Remove the duplicate define (Suggested By:Harry Wentland)

v2: Define this struct in DRM (From Manasi)
* Changed the data types to u8/u16 instead of unsigned longs (Manasi)
* Remove driver specific fields (Manasi)
* Move this struct definition to DRM (Manasi)
* Define DSC 1.2 parameters (Manasi)
* Use DSC_NUM_BUF_RANGES (Manasi)
* Call it drm_dsc_config (Manasi)

Cc: dri-devel@lists.freedesktop.org
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Co-developed-by: Gaurav K Singh <gaurav.k.singh@intel.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Sean Paul <seanpaul@chromium.org> (For merging through
drm-intel)
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181127214125.17658-3-manasi.d.navare@intel.com