drm/amd/display: change the panel power savings level without a modeset

We don't actually need to request that the compositor does a full
modeset to modify the panel power savings level, we can instead
just make a request to DMUB, to set the new level dynamically.

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Sebastian Wick <sebastian@sebastianwick.net>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Tested-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/3578


Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>