drm/amd/display: Partition DPCD address space and break up transactions

[WHY]
SCR for DP 2.0 spec says that multiple LTTPRs must not be accessed in a
single AUX transaction.
There may be other places in future where breaking up AUX accesses is
necessary.

[HOW]
Partition the entire DPCD address space into blocks. When an incoming AUX
request spans multiple blocks, break up the request into multiple requests.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>