Right now the PVH option rom scans for the RSDP from 0xE0000 to
0xE1FFF. This is probobly a typo, it should scan from 0xE0000 to
0xFFFFF.

This is actually an issue on some QEMU versions/machines. For example,
when I run QEMU the RSDP is placed at 0xf5ad0 which will not be picked
up by the current implementation.

This bug still allows a Linux guest to boot (in most configurations) as
the kernel will just scan for the RSDP if one isn't provided.

Signed-off-by: Joe Richey <joerichey@google.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Fixes: 2785dc7b ("optionrom: add new PVH option rom")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>