drm/i915: Remove return type from i915_drm_client_remove_object

There is no need to return anything in the version which was merged and
also the implementation of the !CONFIG_PROC_FS wasn't returning anything,
causing a build failure there.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: e4ae85e3 ("drm/i915: Add ability for tracking buffer objects per client")
Cc: Aravind Iddamsetty <aravind.iddamsetty@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311110104.8TlHVxUI-lkp@intel.com/


Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231113085457.199053-1-tvrtko.ursulin@linux.intel.com