After traversing the lvalue node tree we're fully done computing the
relative address and emitting any pointer arithmetic that might have
been needed. So the temporary that would have been used for that is no
longer needed.

Change-Id: I0a10bff979128f03544d0f8aa860c29f8867973a
Reviewed-on: https://swiftshader-review.googlesource.com/13948Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>