pxe_utils: Support the SAY command

This shows a message for the user. Implement it to keep the user
informed.

Series-to: u-boot
pxe: Support an automatic localboot
It seems that extlinux expects that boards know how to boot a local OS
from attached media. U-Boot currently assumes that boards define a
"localcmd" environment variable to support this. None does.

Provide an automatic means to find a kernel and ramdisk, using common
filenames. This addresses booting on MAAS, at least.
END

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

test/py/tests/test_ut.py

@@ -621,6 +621,7 @@ def setup_localboot_image(cons):
     script = '''DEFAULT local
 
 LABEL local
+  SAY Doing local boot...
   LOCALBOOT 0
 '''
     vmlinux = 'vmlinuz'