drm/amd/display: Change function decide_dp_link_settings to avoid infinite looping

Why:
Function decide_dp_link_settings() loops infinitely when required bandwidth
can't be supported.

How:
Check the required bandwidth against verified_link_cap before trying to
find a link setting for it.
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NBing Guo <bing.guo@amd.com>
Reviewed-by: NJun Lei <Jun.Lei@amd.com>
Acked-by: NAnson Jacob <anson.jacob@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -2399,6 +2399,9 @@ static bool decide_dp_link_settings(struct dc_link *link, struct dc_link_setting
 			initial_link_setting;
 	uint32_t link_bw;
 
+	if (req_bw > dc_link_bandwidth_kbps(link, &link->verified_link_cap))
+		return false;
+
 	/* search for the minimum link setting that:
 	 * 1. is supported according to the link training result
 	 * 2. could support the b/w requested by the timing