public/sysctl: drop unnecessary typedefs and handles

public/sysctl: drop unnecessary typedefs and handles

By virtue of the struct xen_sysctl container structure, most of them
are really just cluttering the name space.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>