efi_loader: initialize console size late

If CONFIG_VIDEO_DM=n we query the display size from the serial console.
Especially when using a remote console the response can be so late that
it interferes with autoboot.

Only query the console size when running an EFI binary.

Add debug output showing the determined console size.

Reported-by: Fabio Estevam <festevam@gmail.com>
Fixes: a9bf024b ("efi_loader: disk: a helper function to create efi_disk objects from udevice")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Tested-by: Fabio Estevam <festevam@denx.de>
Tested-by: Heiko Thiery <heiko.thiery@gmail.com>