[flang] Fix capitalization of "ishft"

We weren't recognizing the ISHFT intrinsic because the code had
incorrectly capitalized it.

Differential Revision: https://reviews.llvm.org/D111449

GitOrigin-RevId: 0620b12209cf7ccc085db0a574b571d08efc1395
diff --git a/lib/Evaluate/fold-integer.cpp b/lib/Evaluate/fold-integer.cpp
index e881808..6795f90 100644
--- a/lib/Evaluate/fold-integer.cpp
+++ b/lib/Evaluate/fold-integer.cpp
@@ -615,7 +615,7 @@
     // Second argument can be of any kind. However, it must be smaller or
     // equal than BIT_SIZE. It can be converted to Int4 to simplify.
     auto fptr{&Scalar<T>::ISHFT};
-    if (name == "ISHFT") { // done in fptr definition
+    if (name == "ishft") { // done in fptr definition
     } else if (name == "shifta") {
       fptr = &Scalar<T>::SHIFTA;
     } else if (name == "shiftr") {