[StackMaps] Remove format version from the class name [NFC]

Motivation is to reduce silly diffs when we change the format.  For instance, this causes most of D59020 to disappear.

llvm-svn: 358322
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 06092b1..2cf2496 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -2407,7 +2407,7 @@
       unwrapOrError(Obj->getSectionContents(StackMapSection));
 
   prettyPrintStackMap(
-      W, StackMapV2Parser<ELFT::TargetEndianness>(StackMapContentsArray));
+      W, StackMapParser<ELFT::TargetEndianness>(StackMapContentsArray));
 }
 
 template <class ELFT> void ELFDumper<ELFT>::printGroupSections() {