drm/amd/display: Don't register panel_power_savings on OLED panels

drm/amd/display: Don't register panel_power_savings on OLED panels

OLED panels don't support the ABM, they shouldn't offer the
panel_power_savings attribute to the user. Check whether aux BL
control support was enabled to decide whether to offer it.

Reported-by: Gergo Koteles <soyer@irl.hu>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3359
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Tested-by: Gergo Koteles <soyer@irl.hu>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>