drm/i915: Clean up some struct/array initializers

Use the simple '= {}' form to initialize empty arrays/structs.
Also add some missing whitespace.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220301173128.6988-4-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>