drm/i915: do not abbreviate version in debugfs

Brevity is not needed here, so just spell out "* version" in the string.

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210707235921.2416911-1-lucas.demarchi@intel.com