drm/i915/perf: fix i915_perf_ioctl_version() kernel-doc

drivers/gpu/drm/i915/i915_perf.c:5307: warning: Function parameter or member 'i915' not described in 'i915_perf_ioctl_version'

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b93ddb95a15d1376936349b32c7facb35c76be82.1683041799.git.jani.nikula@intel.com