[Sparc] Always use the version of computeKnownBits that returns a value. NFCI.

Continues the work started by @bogner in rL340594 to remove uses of the KnownBits output paramater version.

llvm-svn: 349914
diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index 7d908bb..ae22576 100644
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -1866,8 +1866,8 @@
   case SPISD::SELECT_ICC:
   case SPISD::SELECT_XCC:
   case SPISD::SELECT_FCC:
-    DAG.computeKnownBits(Op.getOperand(1), Known, Depth+1);
-    DAG.computeKnownBits(Op.getOperand(0), Known2, Depth+1);
+    Known = DAG.computeKnownBits(Op.getOperand(1), Depth + 1);
+    Known2 = DAG.computeKnownBits(Op.getOperand(0), Depth + 1);
 
     // Only known if known in both the LHS and RHS.
     Known.One &= Known2.One;