drm/amd/display: Update SPL Taps Required For Integer Scaling

drm/amd/display: Update SPL Taps Required For Integer Scaling

Number of taps is incorrectly being set when integer scaling is enabled.
Taps required when src_rect != dst_rect previously not considered.
Perform the calculations when integer scaling is enabled.
Set taps to 1 if the scaling ratio is 1:1.

Reviewed-by: Samson Tam <samson.tam@amd.com>
Signed-off-by: Austin Zheng <Austin.Zheng@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>