efi_loader: Show FirmwareVendor and FirmwareRevision in helloworld

Show the firmware vendor and revision to make it clear which firmware is
used, e.g. whether U-Boot is providing the boot services.

The output will look like

    Firmware vendor: Das U-Boot
    Firmware revision: 20241000

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
1 file changed