i965/compute: Fix uniform init issue when SIMD8 is skipped

i965/compute: Fix uniform init issue when SIMD8 is skipped

In d8347f12ead89c5a58f69ce9283a54ac8487159c, we added support for
skipping SIMD8 generation when the program local size is too large for
SIMD8 to be usable. This change was missed in that commit.

This bug would impact gen7 platforms when the compute shader local
size is greater than 512, and gen8 platforms when the local size is
greater than 448.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>