xen: introduce internal CDF_xxx flags for domain creation

xen: introduce internal CDF_xxx flags for domain creation

We are passing an internal-only boolean flag at domain creation to
specify whether we want the domain to be privileged (i.e. dom0) or
not. Another flag will be introduced later in this series.

This commit extends original "boolean" to an "unsigned int" covering both
the existing "is_priv" and our new "directmap", which will be introduced later.

To make visible the relationship, we name the respective constants CDF_xxx
(with no XEN_DOMCTL_ prefix) to represent the difference with the public
constants XEN_DOMCTL_CDF_xxx.

Allocate bit 0 as CDF_privileged: whether a domain is privileged or not.

Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>