Add bootmode injection support

I tried to cherry-pick the following two commits from the aries kernel:

aries: Add bootmode injection support
10fd786bd425a310b63eb6be4bb8ccf9f7c92f39

aries: Only inject bootmode if bootmode is single digit
43a10baf0aeec07bfc1913b76a29b2a20d0f9c7a

But the changes were too different.
This commit is the manual port of this change.

Change-Id: I498083b591e5ca961203f3a182226f0b679ac866

Conflicts:
	arch/arm/mach-s5pv210/mach-aries.c
	arch/arm/plat-s5p/devs.c
	usr/galaxys4gmtd_initramfs_files/init