MIPS: BCM63xx: Enable second core SMP on BCM6328 if available

BCM6328 has a OTP which tells us if the second core is available.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: John Crispin <blogic@openwrt.org>
Cc: Maxime Bizon <mbizon@freebox.fr>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/5490/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>