fix realm sync permissions

fix realm sync permissions

The userid-* permission check variants work on
$param->{userid} directly which does not exist for this
call. Also, they work on the realm of the user being
checked, rather than the realm provided as parameter.

The result was that as non-root user this always failed
with the message "userid '' too short"

Fix this by making the check explicitly work like in the
description.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>