drm/amd/display: Refactor SubVP calculation to remove FPU

Refactor calculation to remove floating point operations from dmub_srv.
To ensure that 32-bit compilation works well, we use the div64 family of
macros to do integer division for SubVP-related timing parameters.

Cc: Maíra Canal <mairacanal@riseup.net>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Isabella Basso <isabbasso@riseup.net>
Cc: Magali Lemes <magalilemes00@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Samson Tam <Samson.Tam@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Co-developed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Co-developed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>