x86/shadow: adjust some shadow_set_l<N>e() callers

x86/shadow: adjust some shadow_set_l<N>e() callers

Coverity dislikes sh_page_fault() storing the return value into a local
variable but then never using the value (and oddly enough spots this in
the 2- and 3-level cases, but not in the 4-level one). Instead of adding
yet another cast to void as replacement, take the opportunity and drop a
bunch of such casts at the same time - not using function return values
is a common thing to do. (It of course is an independent question
whether ignoring errors like this is a good idea.)

Coverity-ID: 1492856
Coverity-ID: 1492858
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>