drm/amd/display: update bw_calcs to take pipe sync into account (v3)

Properly set all_displays_in_sync so that when the data is
propagated to powerplay, it's set properly and we can enable
mclk switching when all monitors are in sync.

v2: fix logic, clean up
v3: check for blending chains, simplify logic

Acked-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>