drm/i915/dsi/xelpd: Enable mipi dsi support.

Enable MIPI DSI support on ADL-P platform.
The esc clock changes, WA changes are taken care
in the previous patches.
As per the Bspec the seq remains to be same as TGL.

Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210826054811.10572-3-vandita.kulkarni@intel.com