drm/i915/dp: Register definition for DP compliance register

DP_COMP_CTL and DP_COMP_PAT register used to program DP
compliance pattern.

v1: Initial patch.
v2: used pipe instead of port in macro definition. [Manasi]
v3: used trans_offset for offset calculation. [Manasi]
v4: Used MMIO_PIPE for evenly spaced register offset instead
MMIO_PIPE2. [Ville]

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200324051111.29398-1-animesh.manna@intel.com