x86: fix long standing bug with usb after hibernation with 4GB ram

aperture_64.c takes a piece of memory and makes it into iommu
window... but such window may not be saved by swsusp -- that leads to
oops during hibernation.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>