x86/shadow: drop stray name tags from sh_{guest_get,map}_eff_l1e()

x86/shadow: drop stray name tags from sh_{guest_get,map}_eff_l1e()

They (as a now being removed comment validly says) depend only on Xen's
number of page table levels, and hence their tags didn't serve any
useful purpose (there could only ever be one instance in a single
binary, even back in the x86-32 days).

Further conditionalize the inclusion of PV-specific hook pointers, at
once making sure that PV guests can't ever get other than 4-level mode
enabled for them.

For consistency reasons shadow_{write,cmpxchg}_guest_entry() also get
moved next to the other PV-only actors, allowing them to become static
just like the $subject ones do.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>