MIPS: JZ4770: Work around config2 misreporting associativity

According to config2, the associativity would be 5-ways, but the
documentation states 4-ways, which also matches the documented
L2 cache size of 256 kB.
Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Reviewed-by: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/18488/Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/mm/sc-mips.c

@@ -16,6 +16,7 @@
 #include <asm/mmu_context.h>
 #include <asm/r4kcache.h>
 #include <asm/mips-cps.h>
+#include <asm/bootinfo.h>
 
 /*
  * MIPS32/MIPS64 L2 cache handling
@@ -220,6 +221,14 @@ static inline int __init mips_sc_probe(void)
 	else
 		return 0;
 
+	/*
+	 * According to config2 it would be 5-ways, but that is contradicted
+	 * by all documentation.
+	 */
+	if (current_cpu_type() == CPU_JZRISC &&
+				mips_machtype == MACH_INGENIC_JZ4770)
+		c->scache.ways = 4;
+
 	c->scache.waysize = c->scache.sets * c->scache.linesz;
 	c->scache.waybit = __ffs(c->scache.waysize);