ARM: lpc18xx: add basic support for NXP LPC18xx/43xx SoCs

Add support for NXP's LPC18xx (Cortex-M3) and LPC43xx (Cortex-M4)
SoCs. These SoCs are NXP's high preformance MCU line and can run at
clock speeds up to 180 MHz for LPC18xx and 204 MHz for LPC43xx.

LPC43xx is more or less a LPC18xx with a Cortex-M4F core and a few
extra peripherals. The LPC43xx series also features one or two
Cortex-M0 cores that can be used to offload the main M4 core.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>