mini-os: Do not use the same wait element twice
mini-os: Do not use the same wait element twice

To enqueue the kbdfront thread on two separate wait queues, we need
two different wait elements.

Signed-off-by: Samuel Thibault <49a5ed162141aa1a2ad45c2f70540ac844521912@ens-lyon.org>

rowhit/xen-minios,rowhit/xen-minios,rowhit/xen-minios