The real limit is the top of the visible physical address space with
the MMU turned off.  Hence, we need to limit the crash kernel allocation
running-view physical address of the top of the boot-view physical
address space.
Reviewed-by: NPratyush Anand <panand@redhat.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>