[tilegx] Complete FloatingPointHelper::CallCCodeForDoubleOperation fix.

  we expect the incoming arg to be a2/a3, because in function which
invoke CallCCodeForDoubleOperation, a0/a1 are with original left and
right, so we should not clobber them.

  in CallCCodeForDoubleOperation, a2/a3 meant converted left/right,
they are ready to be passed to c emulation function. so we need to
move them to a0/a1 again.
[tilegx] Fixed a couple of 64bit datatype issue.

  We need to use 64bit version for TileGX in these places.