[SYCL][joint matrix spec] clarify coodinates of packed matrix and fix…

… joint_matrix_copy requirements (intel#11299)

sycl/doc/extensions/experimental/sycl_ext_matrix/sycl_ext_intel_matrix.asciidoc

@@ -198,6 +198,11 @@ joint_matrix_apply(sg, A, [=](T &val, size_t row, size_t  col) {
    sum_local_rows[row] += val;
 });
 ```
+
+In the case of `ext_intel_packed` matrix memory layout, `row` and
+`col` represent the coordinates in the logical matrix before VNNI
+transformation.
+
 === New Device Information Descriptor
 Besides the query we provide in
 link:sycl_ext_oneapi_matrix.asciidoc[sycl_ext_oneapi_matrix],

sycl/doc/extensions/experimental/sycl_ext_matrix/sycl_ext_oneapi_matrix.asciidoc

@@ -318,18 +318,18 @@ void joint_matrix_fill(Group g, joint_matrix<Group, T, Use, Rows,
 namespace sycl::ext::oneapi::experimental::matrix {
 
 template <typename Group, typename T1, typename T2, size_t Rows,
-          size_t Cols, use Use1, use Use2, layout Layout> 
+          size_t Cols, use Use1, use Use2, layout Layout1, layout Layout2>
 void joint_matrix_copy(Group g,
-                       joint_matrix<Group, T1, Use1, Rows, Cols, Layout> &src,
-                       joint_matrix<Group, T2, Use2, Rows, Cols, Layout> &dest);
+                      joint_matrix<Group, T1, Use1, Rows, Cols, Layout1> &src,
+                      joint_matrix<Group, T2, Use2, Rows, Cols, Layout2> &dest);
 
 } // namespace sycl::ext::oneapi::experimental::matrix
 ```
 This function copies `Rows x Cols` elements of type `T1` from joint
 matrix `src` to `Rows x Cols` elements of type `T2` of joint matrix
-`dest`. The two matrices must have the same scope, shape, and
-layout. Use and type can be different so this function converts
-between different `use` of matrices.
+`dest`. The two matrices must have the same scope and shape. Use,
+type, and layout can be different so this function converts between
+different `use` of matrices.
 
 ==== Element-Wise Operations
 Besides matrix multiply and add, this extension aims to make it