PTX: add flag to disable mad/fma selection

Patch by Dan Bailey

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131537 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PTX/PTXSubtarget.cpp b/lib/Target/PTX/PTXSubtarget.cpp
index e754290..e8a1dfe 100644
--- a/lib/Target/PTX/PTXSubtarget.cpp
+++ b/lib/Target/PTX/PTXSubtarget.cpp
@@ -21,7 +21,8 @@
   : PTXShaderModel(PTX_SM_1_0),
     PTXVersion(PTX_VERSION_2_0),
     SupportsDouble(false),
-    Is64Bit(is64Bit) {
+    SupportsFMA(true),
+    Is64Bit(is64Bit) {	
   std::string TARGET = "generic";
   ParseSubtargetFeatures(FS, TARGET);
 }