AVX512F implementation of GEMM & IGEMM micro-kernels

PiperOrigin-RevId: 282810752
diff --git a/src/f32-gemm/avx-broadcast.c.in b/src/f32-gemm/avx-broadcast.c.in
index 90d7e08..c7df40f 100644
--- a/src/f32-gemm/avx-broadcast.c.in
+++ b/src/f32-gemm/avx-broadcast.c.in
@@ -3,8 +3,8 @@
 // This source code is licensed under the BSD-style license found in the
 // LICENSE file in the root directory of this source tree.
 
-$assert NR % 4 == 0
-$ABC = "0123456789ABCDEFGHIJKLMN"
+$assert NR % 8 == 0
+$ABC = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 #include <assert.h>
 
 #include <immintrin.h>