drm/xe/vf: Make multi-GT migration less error prone

drm/xe/vf: Make multi-GT migration less error prone

There is a remote chance that after migration,  some GTs will not
send the MIGRATED interrupt, or due to current VF KMD state the
interrupt will not lead to marking the GT for recovery.

Requiring IRQs from all GTs before starting migration introduces
the possibility that the process will get stalled due to one GuC.

One could argue it is also waste of time to wait for all IRQs,
but we should get them all IRQs as soon as VGPU starts, so that's
not really an impactful argument.

Still, not waiting for all GTs makes it easier to handle situations:
* where one GuC IRQ is missing
* where state before probe is unclean - getting MIGRATED IRQ as soon
  as interrupts are enabled
* where multiple migrations happen close to each other

To help with these cases, this patch alters the post-migration
recovery so that recovery task is started as soon as one GuC IRQ
is handled, and other GTs are included in recovery later as the
subsequent IRQs are serviced.

The post-migration recovery can now be called for any selection of
GTs, and it will perform recovery on all GTs for which IRQs have
arrived, even multiple times if necessary.

v2: Typos and style fixes
v3: Transferring gt_flags by value rather than reference to last
 function where it is used

Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Cc: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Acked-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Reviewed-by: Michal Winiarski <michal.winiarski@intel.com>
Link: https://lore.kernel.org/r/20250630152155.195648-1-tomasz.lis@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>