arm: use UART_PPTR for all uarts

include/plat/allwinnerA20/plat/machine/devices.h

include/plat/allwinnerA20/plat/machine/hardware.h

include/plat/am335x/plat/machine/devices.h

include/plat/am335x/plat/machine/hardware.h

include/plat/hikey/plat/32/plat_mode/machine/devices.h

include/plat/hikey/plat/64/plat_mode/machine/devices.h

include/plat/hikey/plat/machine/hardware.h

include/plat/omap3/plat/machine/devices.h

include/plat/omap3/plat/machine/hardware.h

include/plat/tk1/plat/machine/devices.h

include/plat/tx1/plat/machine/devices.h

include/plat/tx1/plat/machine/hardware.h

include/plat/tx2/plat/machine/devices.h

include/plat/tx2/plat/machine/hardware.h

src/plat/allwinnerA20/machine/io.c

src/plat/am335x/machine/io.c

src/plat/hikey/machine/io.c

src/plat/omap3/machine/io.c

src/plat/tk1/machine/io.c

src/plat/tx1/machine/io.c