drm/amd/display: option to maximize lb usage

experimental change for testing if max line buffer result in better stutter efficiency

for 1080p, LB can hold up to 9 line at 10bpcc, potentially add 10 line time of
latency hiding.

Signed-off-by: Tony Cheng <tony.cheng@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>