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: 9f4a0f09 ("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>