Integrate llvm-project @c6ff6d78618a5709d518d5f7f2a59ec62273fd10 (#17978)

Bumps llvm-project to
https://github.com/llvm/llvm-project/commit/168ecd706904d6ce221dc5107da92c56aea7c8e9

Still carrying revert: c6ff6d78618a5709d518d5f7f2a59ec62273fd10 

(TODO: bump torch-mlir and update
to bumped submodule)

---------

Signed-off-by: aviator19941 <avinash.sharma@amd.com>
diff --git a/third_party/llvm-project b/third_party/llvm-project
index 97c0dbe..c6ff6d7 160000
--- a/third_party/llvm-project
+++ b/third_party/llvm-project
@@ -1 +1 @@
-Subproject commit 97c0dbe1ad6dacbcca84e63e9d726b85b65af4fe
+Subproject commit c6ff6d78618a5709d518d5f7f2a59ec62273fd10