drm/i915/xelpmp: Add multicast steering for media GT

MTL's media IP (Xe_LPM+) only has a single type of steering ("OAADDRM")
which selects between media slice 0 and media slice 1.  We'll always
steer to media slice 0 unless it is fused off (which is the case when
VD0, VE0, and SFC0 are all reported as unavailable).

Bspec: 67789
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014230239.1023689-15-matthew.d.roper@intel.com