drm/amd/display: remove dc dependencies from SPL library

[Why]
Make SPL library dc-independent so it can be reused by other
 components

[How]
Create separate set of fixed31_32 calls in SPL
Make all inputs and outputs to SPL use primitive types
For ratios and inits, return as uint32 from SPL.  So
 add conversion from uint32 back to fixed point in
 SPL-to-dc translate function

Reviewed-by: Relja Vojvodic <relja.vojvodic@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Samson Tam <samson.tam@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>