The new MMU setup will need SDRAM base addresses and sizes.
For this reason convert the MMU enabled ARM boards:

- move mem setup to mem_initcall. This is early but
  still makes sure that we already have the console available
- move MMU setup in this initcall temporary as after the mmu_init will generic

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

AT91sam9g20 is an evolution of the at91sam9260 with a faster clock
speed.
We created a new board for this device but based the chip support
directly on 9260 files with little updates.
Here is the chip page on Atmel wabsite:
http://atmel.com/dyn/products/product_card.asp?part_id=4337

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Patrice Vilchez <patrice.vilchez@atmel.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

this will allow each arch to handle the boards more simply and depending on
there need

the env var BOARD will refer to the current board dirent

for sandbox as we have only one board the board dirent is arch/sandbox/board

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>