Following on from the CMOS/RTC port aliasing change, there are some
more missing restrictions; in particular there's more port aliasing to
be aware of. But first of all introduce a command line option to allow
suppressing this probing of aliases, as was requested.

Of course an alternative to all of this would be to do away with all
policy-only ioports_deny_access() in dom0_setup_permissions(), leaving
in place only ones which are truly required for functionality reasons.

1: allow to suppress port-alias probing
2: detect PIC aliasing on ports other than 0x[2A][01]
3: detect PIT aliasing on ports other than 0x4[0-3]

Jan