Draft: scripts: Add deferred_probe_timeout kernel parameter

NOTE: This wasn't tested.

The default deferred_probe_timeout of 10 seconds isn't enough to reliably boot the MediaTek Chromebooks using the upstream defconfig from USB flash disks and no ramdisk. Override it to 30 seconds to make sure all devices can probe reliably while a better solution isn't found upstream.

Signed-off-by: Nícolas F. R. A. Prado nfraprado@collabora.com