[Mini-OS] Make wake_up callback-safe
[Mini-OS] Make wake_up callback-safe

As it may compete with event handlers waking wait queues, wake_up
needs to be callback-safe.

Signed-off-by: Samuel Thibault <49a5ed162141aa1a2ad45c2f70540ac844521912@citrix.com>

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