[RFC] Boot command line support

[Jean-Christophe PLAGNIOL-VILLARD]

HI,

	as barebox is some times a second stage bootloader
	it could be intresting to pass some information

	I'm currently working on two support
	the atags for arm and the cmdline

	The cmline could be static or dynamic
	so it will be easy to customise a boot sequence and etc...

	this first patch will just add static cmdline

	later I'll send dynamic support and arm boot ABI

Best Regards,
J.