replace bogus -ENOSYS uses

replace bogus -ENOSYS uses

This doesn't cover all of them, just the ones that I think would most
obviously better be -EINVAL or -EOPNOTSUPP.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>