drm/i915/hdcp: Use new MST topology state in intel_conn_to_vcpi()

drm/i915/hdcp: Use new MST topology state in intel_conn_to_vcpi()

intel_conn_to_vcpi() runs from the HDCP enable path in commit_tail
and looks up the VCPI via mgr->base.state. When an ALLOCATE_PAYLOAD
is being driven on the mgr just before HDCP enable, that payload
list is being mutated in place, so the lookup can miss the port and
trip drm_WARN_ON(!payload), causing HDCP to be programmed with
VCPI 0.
Use drm_atomic_get_new_mst_topology_state() to read the topology
state attached to this atomic commit (stable, decided in
atomic_check), and bail out cleanly when no topology state or
payload is present for this port instead of WARNing.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Tested-by: Santhosh Reddy Guddati <santhosh.reddy.guddati@intel.com>
Reviewed-by: Santhosh Reddy Guddati <santhosh.reddy.guddati@intel.com>
Link: https://patch.msgid.link/20260504101117.3619984-2-suraj.kandpal@intel.com