[Alignment] Fix old method name in comment. NFC

getValue() was renamed to value() in the migration from
llvm::Optional to std::optional.

Author: topperc

llvm/include/llvm/Support/Alignment.h

@@ -14,7 +14,7 @@
 // power of two, its minimum value is 1 which means no alignment requirements.
 //
 // - MaybeAlign is an optional type, it may be undefined or set. When it's set
-// you can get the underlying Align type by using the getValue() method.
+// you can get the underlying Align type by using the value() method.
 //
 //===----------------------------------------------------------------------===//