[MIPS] Add support for BCM47XX CPUs.

Note that the BCM4710 does not support the wait instruction, this
is not a mistake in the code.
    
It originally comes from the OpenWrt patches.
    
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Felix Fietkau <nbd@openwrt.org>
Cc: Florian Schirmer <jolt@tuxbox.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 6c425b0..b2c6b9e 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -908,6 +908,8 @@
 	case CPU_4KSC:
 	case CPU_20KC:
 	case CPU_25KF:
+	case CPU_BCM3302:
+	case CPU_BCM4710:
 	case CPU_LOONGSON2:
 		if (m4kc_tlbp_war())
 			i_nop(p);