sh: Bump up NODES_SHIFT for SH-X3.

This was at 1, which is where most subtypes want it. SH-X3 has
more nodes, so bump it up to 3.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/mm/Kconfig

@@ -308,6 +308,7 @@ config NUMA
 
 config NODES_SHIFT
 	int
+	default "3" if CPU_SUBTYPE_SHX3
 	default "1"
 	depends on NEED_MULTIPLE_NODES