fix table column widths

Author: bashbaug

extensions/cl_intel_subgroup_matrix_multiply_accumulate.asciidoc

@@ -427,7 +427,7 @@ For devices where the minimum subgroup size is 16, the following matrix dimensio
 For these devices, the subgroup size must be 16 (the minimum subgroup size).
 Behavior is undefined if these functions are called on other devices or from kernels with a different subgroup size:
 
-[cols="7*^",width="100%"]
+[cols="^1,^1,^1,^2,^2,^2,^2",width="100%"]
 [options="header"]
 |=====
 | M Dimension | N Dimension | K Dimension | Result Type | Matrix A Type | Matrix B Type | Matrix C Type