drm/amd/display: Reduce default backlight min from 5 nits to 1 nits

[Why & How]
Currently set_default_brightness_aux function uses 5 nits as lower limit
to check for valid default_backlight setting. However some newer panels
can support even lower default settings

Reviewed-by: Agustin Gutierrez <agustin.gutierrez@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Swapnil Patel <swapnil.patel@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Swapnil Patel

drivers/gpu/drm/amd/display/dc/link/protocols/link_edp_panel_control.c

@@ -283,8 +283,8 @@ bool set_default_brightness_aux(struct dc_link *link)
 	if (link && link->dpcd_sink_ext_caps.bits.oled == 1) {
 		if (!read_default_bl_aux(link, &default_backlight))
 			default_backlight = 150000;
-		// if < 5 nits or > 5000, it might be wrong readback
-		if (default_backlight < 5000 || default_backlight > 5000000)
+		// if < 1 nits or > 5000, it might be wrong readback
+		if (default_backlight < 1000 || default_backlight > 5000000)
 			default_backlight = 150000; //
 
 		return edp_set_backlight_level_nits(link, true,