drm/xe: Remove fence check from send_tlb_invalidation

drm/xe: Remove fence check from send_tlb_invalidation

'fence' argument in send_tlb_invalidation cannot be NULL, remove
non-NULL check from send_tlb_invalidation.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202407231049.esig0Fkb-lkp@intel.com/
Fixes: 61ac035361ae ("drm/xe: Drop xe_gt_tlb_invalidation_wait")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240723190714.1744653-1-matthew.brost@intel.com
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>