isl: fix automake build when sse41 is not supported

Fixes: 864cc419 "intel/isl: move tiled_memcpy static libs from i965 to isl"
Cc: mesa-stable@lists.freedesktop.org
Reported-by: Milav Soni <milav.soni@teqdiligent.com>
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
(cherry picked from commit a1cd0040)