ciaa-nxp: Improve linker script, so it links with modern toolchains

The ORIGIN(...) in linker sections must be constant expressions,
so we get rid of the math operations. This means the memory macros
for the base addresses now have to be properly defined in the boards'
config header.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
board: Add support for CIAA NXP LPC4337

This configuration adds support for:

  * GPIO
  * USART3 as console
  * Ethernet (which allows netbooting a kernel)
  * SDRAM
  * SPIFI (half-baked for now)

The image created is ready to be written to the MCU internal flash,
as we take care of putting the proper header expected by the BootROM.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>