drm/i915/params: don't expose inject_probe_failure in debugfs

The parameter only makes sense as a module parameter only.

Fixes: c43c5a88 ("drm/i915/params: add i915 parameters to debugfs")
Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila@intel.com>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200601215510.18379-1-jani.nikula@intel.com
(cherry picked from commit dbf4081f)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_params.h

@@ -64,7 +64,7 @@ struct drm_printer;
 	param(int, mmio_debug, -IS_ENABLED(CONFIG_DRM_I915_DEBUG_MMIO), 0600) \
 	param(int, edp_vswing, 0, 0400) \
 	param(unsigned int, reset, 3, 0600) \
-	param(unsigned int, inject_probe_failure, 0, 0600) \
+	param(unsigned int, inject_probe_failure, 0, 0) \
 	param(int, fastboot, -1, 0600) \
 	param(int, enable_dpcd_backlight, -1, 0600) \
 	param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE, 0400) \