xics: Eliminate 'reject', 'resend' and 'eoi' class hooks

xics: Eliminate 'reject', 'resend' and 'eoi' class hooks

Currently ics_reject(), ics_resend() and ics_eoi() indirect through
class methods.  But there's only one implementation of each method,
the one in TYPE_ICS_SIMPLE.  TYPE_ICS_BASE has no implementation, but
it's never instantiated, and has no other subtypes.

So clean up by eliminating the method and just having ics_reject(),
ics_resend() and ics_eoi() contain the logic directly.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>