Move handling of vget_lane/vset_lane before the code that checks the type.

Unlike most of the other Neon intrinsics, these are not overloaded and do not
have the extra argument that specifies the vector type.  This has not been
fatal because the lane number operand is supposed to be an ICE and so that
value has harmlessly been used as the type identifier.  Radar 9901281.

llvm-svn: 137550