MIPS: X1000: Add X1000 system type.

Add X1000 system type for cat /proc/cpuinfo to give out X1000.

Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: ralf@linux-mips.org
Cc: paul@crapouillou.net
Cc: jhogan@kernel.org
Cc: fancer.lancer@gmail.com
Cc: chenhc@lemote.com
Cc: tglx@linutronix.de
Cc: gregkh@linuxfoundation.org
Cc: armijn@tjaldur.nl
Cc: syq@debian.org
Cc: jiaxun.yang@flygoat.com