Fix typo in comment, NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282399 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Krzysztof Parzyszek

include/llvm/MC/MCRegisterInfo.h

@@ -579,8 +579,9 @@ class MCRegUnitIterator : public MCRegisterInfo::DiffListIterator {
   }
 };
 
-/// MCRegUnitIterator enumerates a list of register units and their associated
-/// lane masks for Reg. The register units are in ascending numerical order.
+/// MCRegUnitMaskIterator enumerates a list of register units and their
+/// associated lane masks for Reg. The register units are in ascending
+/// numerical order.
 class MCRegUnitMaskIterator {
   MCRegUnitIterator RUIter;
   const unsigned *MaskListIter;