drm/amd/display: add clear_tiling mi callbacks

This adds clear_tiling callbacks to the mi structure that
will be used for drm panic support to clear the tiling on
a display.  Mem input (mi) is used on DCE based display
IPs.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Lu Yao <yaolu@kylinos.cn>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Harry Wentland <harry.wentland@amd.com>