Don't apply _Py_OPCODE twice (#97986)

It's already applied in PyInstDecoder::opcode.
Applying it twice returns incorrect result on big endian systems.

This change fixes 14 tests in test/functorch/test_dims.py on big endian systems.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97986
Approved by: https://github.com/Skylion007, https://github.com/kit1980
diff --git a/functorch/csrc/dim/dim.cpp b/functorch/csrc/dim/dim.cpp
index f204167..591b7a0 100644
--- a/functorch/csrc/dim/dim.cpp
+++ b/functorch/csrc/dim/dim.cpp
@@ -1427,7 +1427,7 @@
 // dim() --------------------
 
 bool relevant_op(_Py_CODEUNIT c) {
-    switch(_Py_OPCODE(c)) {
+    switch(c) {
         case STORE_NAME:
         case STORE_GLOBAL:
         case STORE_FAST: