chardev-spice: add missing module_obj directive

The chardev-spicevmc class was not listed in chardev/spice.c, causing
"-chardev spicevmc" to fail when modules are enabled.

Reported-by: Frederic Bezies <fredbezies@gmail.com>
Fixes: 9f4a0f0978 ("modules: use modinfo for qom load", 2021-07-09)
Resolves: //gitlab.com/qemu-project/qemu/-/issues/488
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210719164435.1227794-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

chardev/spice.c

@@ -382,6 +382,7 @@ static const TypeInfo char_spicevmc_type_info = {
     .parent = TYPE_CHARDEV_SPICE,
     .class_init = char_spicevmc_class_init,
 };
+module_obj(TYPE_CHARDEV_SPICEVMC);
 
 static void char_spiceport_class_init(ObjectClass *oc, void *data)
 {