Adapt default boot options for USB boot

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
Revert "Delay after hub power on up to 10 seconds."

This reverts commit 7e640e80fdd370315343b31c3693af0e14a1bcb9.
Backport usb hub reset code from upstream

Signed-off-by: Andreas Färber <andreas.faerber@web.de>