remote: enforce VIR_TYPED_PARAM_STRING_OKAY flag on client side serialization

remote: enforce VIR_TYPED_PARAM_STRING_OKAY flag on client side serialization

Commit 8cd1d54 consolidates both daemon and remote driver typed param
serialization functions. The consolidation now enforces client to use
VIR_TYPED_PARAM_STRING_OKAY flag to properly serialize string parameters, which
server has used for quite some time now. And this caused an issue, since the
commit had not adjusted client remote calls appropriately, thus causing a
failure in blkiotune, numatune and migration APIs (as per Xen CI tests). This
patch adjusts both remote_driver.c and gendispatch.pl to properly address this
issue.

http://lists.xenproject.org/archives/html/xen-devel/2016-02/msg01012.html

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Erik Skultety <eskultet@redhat.com>