[Arm] Fix -Wimplicit-fallthrough warnings. NFCI.

llvm-svn: 307375
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 1731dbe..1129826 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5249,6 +5249,7 @@
 
     // Fall though for the Identifier case that is not a register or a
     // special name.
+    LLVM_FALLTHROUGH;
   }
   case AsmToken::LParen:  // parenthesized expressions like (_strcmp-4)
   case AsmToken::Integer: // things like 1f and 2b as a branch targets