ARM: make sure we keep inline asm operands tied.

When patching inlineasm nodes to use GPRPair for 64-bit values, we
were dropping the information that two operands were tied, which
effectively broke the live-interval of vregs affected.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188643 91177308-0d34-0410-b5e6-96231b3b80d8