drm/amd/display: Fix 64 bit divisions on 32 bit platforms by using div64 API

[why]
Synchronization displays with different timings feature uses division
operator for 64 bit division, which is not supported by 32 bit platforms

[how]
Use div64 API for 64 bit division

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>