driver: flash: update function prototype

As the load function re-defined, so update the flash load
function accordingly.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
driver: makefile: assemble also need FLASH flags

Signed-off-by: Bo Shen <voice.shen@atmel.com>
config: make option for flash configurable

Signed-off-by: Bo Shen <voice.shen@atmel.com>
main: enable to init flash load function

Signed-off-by: Bo Shen <voice.shen@atmel.com>
crt0: initial clock through c code

As the boot code has been relocated to sram, so configure clock
in sram directly.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
board: sama5d3xek: initialize onboard nor flash

Add function to initialize the on board nor flash.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
board: sama5d3xek: add ALLOW_FLASH option

Signed-off-by: Bo Shen <voice.shen@atmel.com>
board: sama5d3xek: add nor boot to u-boot defconfig

Signed-off-by: Bo Shen <voice.shen@atmel.com>
flash: sama5d3xek: move the norflash_hw_init() declearation to the board header file

By convention, aligned with other booting mode.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Config: NOR flash: indicate support to boot from the NOR flash is depended on the ROM Code version

Booting from the NOR flash is supported form ROM Code v2.1.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
README: update: add information of booting form the NOR flash

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>