drm/xe/pf: Trigger explicit FLR while disabling VFs

We attempt to unprovision all VFs GuC when disabling them, but
GuC may reject such request if the target VF was previously active
but VF driver didn't unload with explicit VF reset H2G action or
the VMM has not started the VF FLR.

To avoid mismatches between configs maintained the PF and GuC,
trigger an explicit FLR sequences just before releasing resources.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240625194546.1301-2-michal.wajdeczko@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>