drm/amd/display: Fix 64 bit modulus operation using div64 API

[why]
Synchronization displays with different timings feature uses
reminder of 64 bit division (modulus operator) , which is not
supported by 32 bit platforms

[how]
Use div64 API for 64 bit modulus

Signed-off-by: Vladimir Stempen <vladimir.stempen@amd.com>
Tested-by: Bindu <Ramamurthy&lt;bindu.r@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>