x86/hvm: Drop more remains of the PVHv1 implementation

x86/hvm: Drop more remains of the PVHv1 implementation

These functions don't need is_hvm_{vcpu,domain}() predicates.

hvmop_set_evtchn_upcall_vector() does need the predicate to prevent a PV
caller accessing the hvm union, but swap the copy_from_guest() and
is_hvm_domain() predicate to avoid reading the hypercall parameter if we not
going to use it.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>