PXA: Cleanup serial_pxa

* Cleanup register definitions by introducing new regs-uart.h, compliant with
  rest of U-Boot.
* Remove old register definitions from pxa-regs.h
* Convert serial_pxa to new regs-uart.h
* Cleanup serial_pxa

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
3 files changed