Implement a Xen back-end for hvc console.
* * *
Add early printk support via hvc console, enable using
"earlyprintk=xen" on the kernel command line.
From: Gerd Hoffmann
Signed-off-by: Jeremy Fitzhardinge
Signed-off-by: Chris Wright
Acked-by: Ingo Molnar
Acked-by: Olof Johansson