Fix code causing fallthrough warnings in the PPC back end.

llvm-svn: 320806
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index e047179..879bb4c 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -2415,6 +2415,7 @@
       NewImm = Addend + SExtImm;
       break;
     }
+    return false;
   }
   case PPC::RLDICL:
   case PPC::RLDICLo: