drm/amd/display: Multiplane cursor position incorrect when plane rotated

[Why]
When video plane is rotate the cursor position is incorrect and not
matching the desktop location.

[How]
When a plane is rotated 90 or 270 degrees, the src_rect.width and height
should be swapped when determining the scaling factor compared to the
dst_rect.

Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bindu Ramamurthy <bindu.r@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>