drm/dp: Kill total_pbn and total_slots in struct drm_dp_mst_topology_mgr

The total vcpi time slots is always 63 and does not depend on the link BW,
remove total_slots from MST topology manager struct. The next change is to
remove total_pbn which is hardcoded to 2560. The total PBN that the
topology manager allocates from depends on the link rate and is not a
constant. So, fix this by removing the total_pbn member itself.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Harry Wentland <Harry.wentland@amd.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1489648231-30700-2-git-send-email-dhinakaran.pandiyan@intel.com