Introduce XMEGA EBI driver. This enable EBI for use with all memory
supported by the device and peripherals. It include support to SRAM,
SDRAM, LCDs or any other external bus access.
Note: This feature only works for A1/A1U series, which are, the series
with EBI hardware.
Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>
