Michael Brown
b9ef880c8d
[romprefix] Treat 0xffffffff as an error return from PMM
PMM defines the return code 0xffffffff as meaning "unsupported
function". It's hard to imagine a PMM BIOS that doesn't support
pmmAllocate(), but apparently such things do exist.
Signed-off-by: Michael Brown <mcb30@ipxe.org>