[AMD] Fix constexpr equality check (#7034)

The existing code is checking `val in (elem)`, but `()` doesn't define a
tuple, `(elem,)` does. As a result, this is actually check if the
element contains val, which is a subtle unsafe bug, that hopefully never
has practical implications.

Author: njriasan

third_party/amd/backend/driver.py

@@ -213,7 +213,7 @@ def _extracted_type(ty):
             return f"[{val}]"
         if ty[0] == '*':
             return "PyObject*"
-        if ty in ("constexpr"):
+        if ty == "constexpr":
             return "PyObject*"
         return ty_to_cpp(ty)
 
@@ -223,7 +223,7 @@ def format_of(ty):
             return f"({val})"
         if ty[0] == '*':
             return "O"
-        if ty in ("constexpr"):
+        if ty == "constexpr":
             return "O"
         return {
             "float": "f",