drm/xe/pf: Use migration-friendly context IDs auto-provisioning

drm/xe/pf: Use migration-friendly context IDs auto-provisioning

Instead of trying very hard to find the largest fair number of GuC
context IDs that could be allocated for VFs on the current GT, pick
some smaller rounded down to power-of-two value that is more likely
to be provisioned in the same manner by the other PF instance:

 num VFs | num contexts
 --------+-------------
  63..32 | 1024
  31..16 | 2048
  15..8  | 4096
   7..4  | 8192
   3..2  | 16384
      1  | 32768 (regular PF)
      1  | 64512 (admin only PF)

Add also helper function to determine if the PF is admin-only,
and for now use .probe_display flag for that.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://patch.msgid.link/20251105183253.863-2-michal.wajdeczko@intel.com