sh: Prepare for dynamic PMB support

To allow the MMU to be switched between 29bit and 32bit mode at runtime
some constants need to swapped for functions that return a runtime
value.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/addrspace.h

@@ -57,5 +57,11 @@
 #define P3_ADDR_MAX		P4SEG
 #endif
 
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_PMB
+extern int __in_29bit_mode(void);
+#endif /* CONFIG_PMB */
+#endif /* __ASSEMBLY__ */
+
 #endif /* __KERNEL__ */
 #endif /* __ASM_SH_ADDRSPACE_H */