x86/mm: drop guest_{map,get_eff}_l1e() hooks

x86/mm: drop guest_{map,get_eff}_l1e() hooks

Disallow the unmaintained and presumed broken translated-but-not-
external paging mode combination, allowing the respective paging hooks
to go away (which eliminates one pair of NULL callbacks in HAP mode).
As a result of them no longer being generic paging operations, make the
inline functions private to mm.c, dropping their struct vcpu parameters
where suitable.

The enforcement of the proper mode combination gets now done in
paging_enable(), requiring shadow_domctl() to no longer call
shadow_enable() directly.

Also as a result support for XEN_DOMCTL_SHADOW_OP_ENABLE_TRANSLATE gets
removed too.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Tim Deegan <tim@xen.org>