Revert "[Hexagon][Test] Remove undef and infinite loop from test"

Bots are unhappy:

/Users/buildslave/jenkins/workspace/clang-stage1-cmake-RA-incremental/llvm/test/CodeGen/Hexagon/swp-const-tc2.ll:10:14: error: CHECK-NOT: excluded string found in input
; CHECK-NOT: = mpy
             ^
<stdin>:22:6: note: found here
 r5 += mpyi(r2,r3)
     ^~~~~

This reverts commit r341046.

llvm-svn: 341049

llvm/test/CodeGen/Hexagon/swp-const-tc2.ll

@@ -9,14 +9,14 @@
 ; CHECK: = mpy
 ; CHECK-NOT: = mpy
 
-define i32 @f0(i32* %a0) {
+define void @f0() {
 b0:
   br label %b1
 
 b1:                                               ; preds = %b1, %b0
   %v0 = phi i32 [ 0, %b0 ], [ %v9, %b1 ]
   %v1 = phi i32 [ 0, %b0 ], [ %v8, %b1 ]
-  %v2 = load i32, i32* %a0, align 4
+  %v2 = load i32, i32* undef, align 4
   %v3 = add nsw i32 %v1, 1
   %v4 = srem i32 %v2, 3
   %v5 = icmp ne i32 %v4, 0
@@ -32,5 +32,5 @@ b2:                                               ; preds = %b1
   br label %b3
 
 b3:                                               ; preds = %b3, %b2
-  ret i32 %v11
+  br label %b3
 }