efi: add function to determine type of device path ...

Thanks to the wonders of UEFI we have to walk down the
device path all the way until we arrive at the device
we got this path from...

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add initial EFI architecture support ...

This adds support for running barebox in an EFI environment
on X86 PC hardware.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>