Move imx debug-macro.S over to common debug macro directory. It
removes the inclusion to hardware.h by hard-coding the physical
address of uart port and copying IMX_IO_P2V from hardware.h.
Since we will need a common solution, which might use a fixed virtual
address for uart port across platforms, we make a copy of IMX_IO_P2V
here as a temporary solution to enable low-level debug for imx
multi-platform build.