vl: fix 'name' option to work with -readconfig

The 'name' option silently failed when used in config files
( http://lists.gnu.org/archive/html/qemu-devel/2014-04/msg00378.html

 )

-readconfig stores the configuration read in QemuOpts.  Command line
option parsing should do the same, and no more.  In particular it should
not act upon the option.  That needs to be done separately, where both
command line and -readconfig settings are visible in QemuOpts.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: William Dauchy <william@gandi.net>
Tested-by: William Dauchy <william@gandi.net>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(mjt: added commit message by ambru@ and subject prefix)