mvsource: add new command to burn and run scripts

	- add 'mvsource' command to burn U-Boot scripts to flash
	  and run burned scripts (using 'source' command).
	- add 'run_script' environment variable, when set to 'yes'
	  run burned script from flash on late boot stage (in 'misc_init_r')
	** scripts' image is compiled using the mkimage tool
	** scripts can be fetched from TFTP or USB.

Change-Id: Icca6a396fc78a9080d78717ac89cd273544e7b7f
Signed-off-by: Bassel Saba <basselsa@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/19022
Reviewed-by: Omri Itach <omrii@marvell.com>
Tested-by: Star_Automation <star@marvell.com>
6 files changed