Debian: Abolish $suite and $xopts{Suite} from preseed_* interfaces.

Debian: Abolish $suite and $xopts{Suite} from preseed_* interfaces.

Generating a preseed for a suite which does not match the ->{Suite} of
the underlying guest or host object does not seem useful, so remove
this option and use ->{Suite} instead.

For guests ->{Suite} is set by debian_guest_suite() (which is called
from preseed_guest_create(), although it is often also called prior to
that) and by selectguest()

For hosts $ho->{Suite} is initialised by selecthost if we are in the
context of a $job (and if we aren't we had best not be trying to
reinstall a host).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>