drm/i915: Fix i915_inject_load_error() name to read *_probe_*

Commit 50d84418 ("drm/i915: Add i915 to i915_inject_probe_failure")
introduced new functions unfortunately named incompatibly with rules
established by commit f2db53f1 ("drm/i915: Replace "_load" with
"_probe" consequently").  Fix it for consistency.

Suggested-by: Michał Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Cc: Michał Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Tomasz Lis <tomasz.lis@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191029102036.6326-2-janusz.krzysztofik@linux.intel.com