MIPS: Add more CPU identifiers for Octeon II CPUs.

The CPU identifiers for cn68XX, cn66XX and cn61XX are known, so add
them.
Signed-off-by: NDavid Daney <david.daney@cavium.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2776/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/cpu.h

@@ -135,6 +135,9 @@
 #define PRID_IMP_CAVIUM_CN50XX 0x0600
 #define PRID_IMP_CAVIUM_CN52XX 0x0700
 #define PRID_IMP_CAVIUM_CN63XX 0x9000
+#define PRID_IMP_CAVIUM_CN68XX 0x9100
+#define PRID_IMP_CAVIUM_CN66XX 0x9200
+#define PRID_IMP_CAVIUM_CN61XX 0x9300
 
 /*
  * These are the PRID's for when 23:16 == PRID_COMP_INGENIC