[clang] [llvm] [HLSL] Add matrix support to atan2 (PR #194984)

[Farzon Lotfi via cfe-commits]

================
@@ -23,6 +23,11 @@ float4 test_binary_double4(double4 p0) {
   return FUNC(p0, p0);
 }
 
+float4x4 test_binary_double4x4(double4x4 p0) {
+  // ATAN2: warning: '[[FUNC]]<4U, 4U>' is deprecated: In 202x 64 bit API lowering for [[FUNC]] is deprecated. Explicitly cast parameters to 32 or 16 bit types.
----------------
farzonl wrote:

I don't love creating a special check for ATAN2. I suspect you did this because you can't check the other overloads yet because  we haven't implemented those intrinsics in the header. 

Instead of doing this create a `CHECK-MAT`. Then as we add matrix support to the other intrinsics we can reuse this checl. And then when all the other functions get matrix support we can remove that check.

https://github.com/llvm/llvm-project/pull/194984