sama5d3: support sama5d36 chip

Signed-off-by: Josh Wu <josh.wu@atmel.com>
at91: change default bootcmd to bootz, which to load zImage kernel

change boards includes: at91sam9m10g45ek, at91sam9n12ek, at91sam9x5ek
and sama5d3xek.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
at91sam9g20: change default bootcmd to bootz, which to load zImage.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
env: dataflash: fix env_init issue

As the SPI controller is not initialized before env_init(), it causes
reading env in dataflash failed. So, although saveenv() successfully,
it shows warning information when reboot the system as following:

  *** Warning - bad CRC, using default environment

Let the env_relocate() to check env CRC and import it.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>