drm/xe: Move survivability back to xe

Commit d40f275d ("drm/xe: Move survivability entirely to xe_pci")
moved the survivability handling to be done entirely in the xe_pci
layer. However there are some issues with that approach:

1) Survivability mode needs at least the mmio initialized, otherwise it
   can't really read a register to decide if it should enter that state
2) SR-IOV mode should be initialized, otherwise it's not possible to
   check if it's VF

Besides, as pointed by Riana the check for
xe_survivability_mode_enable() was wrong in xe_pci_probe() since it's
not a bool return.

Fix that by moving the initialization to be entirely in the xe_device
layer, with the correct dependencies handled: only after mmio and sriov
initialization, and not triggering it on error from
wait_for_lmem_ready(). This restores the trigger behavior before that
commit. The xe_pci layer now only checks for "is it enabled?",
like it's doing in xe_pci_suspend()/xe_pci_remove(), etc.

Cc: Riana Tauro <riana.tauro@intel.com>
Fixes: d40f275d ("drm/xe: Move survivability entirely to xe_pci")
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250314-fix-survivability-v5-1-fdb3559ea965@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>