drm/xe/vf: Send RESFIX_DONE message at end of VF restore

drm/xe/vf: Send RESFIX_DONE message at end of VF restore

After restore, GuC will not answer to any messages from VF KMD until
fixups are applied. When that is done, VF KMD sends RESFIX_DONE
message to GuC, at which point GuC resumes normal operation.

This patch implements sending the RESFIX_DONE message at end of
post-migration recovery.

v2: keep pm ref during whole recovery, style fixes (Michal)
v3: assert removal to separate patch, debug message per GuC instead
  of one, comments changes (Michal)
v4: improve one debug message (Michal)

Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241104213449.1455694-4-tomasz.lis@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>