drm/amd/display: only check available pipe to disable vbios mode.

[Why & How]
1. only need to check first ODM pipe.
2. Only need to check eDP which is on.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>