qom: cpu: fix parsed feature string length

qom: cpu: fix parsed feature string length

since commit ( 9262685b cpu: Factor out cpu_generic_init() )
features parsed by it were truncated only to the 1st feature
after CPU name due to fact that

   featurestr = strtok(NULL, ",");
   cc->parse_features(cpu, featurestr, &err);

would extract exactly one feature and parse_features() callback
would parse it and only it leaving the rest of features ignored.

Reuse approach from x86 custom impl. i.e. replace strtok() token
parsing with g_strsplit(), which would split feature string in
2 parts name and features list and pass the later to
parse_features() callback.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1503592308-93913-2-git-send-email-imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>