Fix a tblgen bug.

Given the pattern below as an example:
list<dag> Pattern = [(set RC:$dst, (v4f32 (shufp:src3 RC:$src1,
                            (mem_frag addr:$src2))))];

The right reference resolving should lead to:
list<dag> Pattern = [(set VR128:$dst, (v4f32 (shufp:src3 VR128:$src1,
                            (mem_frag addr:$src2))))];
But was yielding:
list<dag> Pattern = [(set VR128:$dst, (v4f32 (shufp VR128:$src1,
                            (mem_frag addr:$src2))))];

Fix this by passing the right name when creating a new DagInit node.

llvm-svn: 106670