Factor ARM triple parsing out of ARMSubtarget. Another step towards making ARM subtarget info available to MC.

llvm-svn: 134569
diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index 39a3528..6d3a42f 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -27,7 +27,7 @@
                                    "Enable VFP3 instructions">;
 def FeatureNEON : SubtargetFeature<"neon", "ARMFPUType", "NEON",
                                    "Enable NEON instructions">;
-def FeatureThumb2 : SubtargetFeature<"thumb2", "ThumbMode", "Thumb2",
+def FeatureThumb2 : SubtargetFeature<"thumb2", "HasThumb2", "true",
                                      "Enable Thumb2 instructions">;
 def FeatureNoARM  : SubtargetFeature<"noarm", "NoARM", "true",
                                      "Does not support ARM mode execution">;