sh: Use the generic I/O port base for slowdown.

This fixes up the build and behaviour for various configurations. Namely
the CONFIG_32BIT cases where legacy mappings do not exist, as well as the
sh64 build.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/machvec.c

@@ -135,5 +135,9 @@ void __init sh_mv_setup(void)
 	if (!sh_mv.mv_nr_irqs)
 		sh_mv.mv_nr_irqs = NR_IRQS;
 
+#ifdef P2SEG
 	__set_io_port_base(P2SEG);
+#else
+	__set_io_port_base(0);
+#endif
 }