drm/i915/icl: Define T_INIT_MASTER registers

This patch defines DSI_T_INIT_MASTER register for DSI ports
0/1 which will be used in dphy programming.

Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1531215614-6828-5-git-send-email-madhav.chauhan@intel.com