We do not set up any kind of virtual addressing before invoking an
ELFBoot image.  Reject if the image's program headers indicate that
virtual addresses are not equal to physical addresses.

This avoids problems when loading some RHEL5 kernels, which seem to
include ELFBoot headers using virtual addressing.  With this change,
these kernels are no longer detected as ELFBoot, and so may be
(correctly) detected as bzImage instead.

Reported-by: Torgeir.Wulfsberg@kongsberg.com
Signed-off-by: Michael Brown <mcb30@ipxe.org>