Add missing magic number checks
Add missing magic number checks

We should sanity check the magic number in an event channel whenever one is
passed to an EVTCHN method or when one is recovered from a list.

Signed-off-by: Paul Durrant <dba6cd059c0054f8a3c62ba902cd9d7238853ee4@citrix.com>

omeg/xenbus,rneilturner/xenbus,QubesOS/qubes-vmm-xen-win-pvdrivers-xenbus,MarkKMueller/xenbus,QubesOS/qubes-vmm-xen-win-pvdrivers-xenbus,omeg/xenbus,MarkKMueller/xenbus,rneilturner/xenbus,QubesOS/qubes-vmm-xen-win-pvdrivers-xenbus,omeg/xenbus,MarkKMueller/xenbus,rneilturner/xenbus