ARMv7k: use Cortex-A7 by default even for tvOS

Also actually test the default CPU from those triples.

llvm-svn: 260621
diff --git a/llvm/lib/Support/Triple.cpp b/llvm/lib/Support/Triple.cpp
index 1485d8e..12aa7bf 100644
--- a/llvm/lib/Support/Triple.cpp
+++ b/llvm/lib/Support/Triple.cpp
@@ -1412,6 +1412,7 @@
   case llvm::Triple::MacOSX:
   case llvm::Triple::IOS:
   case llvm::Triple::WatchOS:
+  case llvm::Triple::TvOS:
     if (MArch == "v7k")
       return "cortex-a7";
     break;