drm/i915/uc: Don't sanitize guc_log_level modparam

We are already storing runtime value of log level in private
field, so there is no need to modify modparam.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@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/20190725205106.36148-1-michal.wajdeczko@intel.com