Convert loglevel-related kernel boot parameters to early_param

So we can use them for the early console like console=uart8250 or
earlycon=uart8250 or early_printk

Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>