drm/amd/display: Check for invalid input params when building scaling params

[WHY]
Function to calculate scaling ratios can be called with invalid plane
src/dest, causing a divide by zero.

[HOW]
Fail building scaling params if plane state src/dest rects are
unpopulated

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>