drm/amd/display: Fix access of wrong array element TF format conversion

Found by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/dce110/dce110_hw_sequencer.c:357
convert_to_custom_float() error: buffer overflow 'arr_points' 2 <= 2
drivers/gpu/drm/amd/amdgpu/../display/dc/dce110/dce110_hw_sequencer.c:358
convert_to_custom_float() warn: buffer overflow 'arr_points' 2 <= 2

Regression:
drm/amd/display: Remove extra arr_points element

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>