drm/i915/dmc: simplify stepping info initialization
Having intel_get_stepping_info() return the pointer that was passed in
isn't necessary. Just use a pointer to the local variable instead.
The initialization to ** didn't make a difference, because it was always
overridden.
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://patch.msgid.link/c9affb82fd3e9fb464778013bb7c8fab06232bfd.1773663208.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>