sh: New extended page flag to wire/unwire TLB entries

Provide a new extended page flag, _PAGE_WIRED and an SH4 implementation
for wiring TLB entries and use it in the fixmap code path so that we can
wire the fixmap TLB entry.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
diff --git a/arch/sh/include/asm/tlb.h b/arch/sh/include/asm/tlb.h
index da8fe7a..3ed2f7a 100644
--- a/arch/sh/include/asm/tlb.h
+++ b/arch/sh/include/asm/tlb.h
@@ -97,6 +97,22 @@
 
 #define tlb_migrate_finish(mm)		do { } while (0)
 
+#ifdef CONFIG_CPU_SH4
+extern void tlb_wire_entry(struct vm_area_struct *, unsigned long, pte_t);
+extern void tlb_unwire_entry(void);
+#else
+static inline void tlb_wire_entry(struct vm_area_struct *vma ,
+				  unsigned long addr, pte_t pte)
+{
+	BUG();
+}
+
+static inline void tlb_unwire_entry(void)
+{
+	BUG();
+}
+#endif /* CONFIG_CPU_SH4 */
+
 #else /* CONFIG_MMU */
 
 #define tlb_start_vma(tlb, vma)				do { } while (0)