fdc: Remove user_creatable flag from sysbus-fdc & SUNW,fdtwo

fdc: Remove user_creatable flag from sysbus-fdc & SUNW,fdtwo

sysbus-fdc and SUNW,fdtwo devices need IRQs to be wired and mmio
to be mapped, and can't be used with -device. Unset
user_creatable on their device classes.

Cc: John Snow <[email protected]>
Cc: Kevin Wolf <[email protected]>
Cc: Marcel Apfelbaum <[email protected]>
Cc: Max Reitz <[email protected]>
Cc: [email protected]
Cc: Thomas Huth <[email protected]>
Acked-by: John Snow <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Acked-by: Marcel Apfelbaum <[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>
Message-Id: <20170503203604[email protected]>
Signed-off-by: Eduardo Habkost <[email protected]>