drm/xe: Allow to inject error in early probe

drm/xe: Allow to inject error in early probe

Allow to test if driver behaves correctly when xe_pcode_probe_early()
fails. Note that this is not sufficient for testing survivability mode
as it's still required to read the hw to check for errors, which doesn't
happen on an injected failure.

To complete the early probe coverage, allow injection in the other
functions as well: xe_mmio_probe_early() and xe_device_probe_early().

Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250314-fix-survivability-v5-3-fdb3559ea965@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>