sh: Generalise the pte handling code for the fixmap path

Generalise the code for setting and clearing pte's and allow TLB entries
to be pinned and unpinned if the _PAGE_WIRED flag is present.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
diff --git a/arch/sh/include/asm/fixmap.h b/arch/sh/include/asm/fixmap.h
index 5ac1e40..1566d33 100644
--- a/arch/sh/include/asm/fixmap.h
+++ b/arch/sh/include/asm/fixmap.h
@@ -65,6 +65,7 @@
 
 extern void __set_fixmap(enum fixed_addresses idx,
 			 unsigned long phys, pgprot_t flags);
+extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
 
 #define set_fixmap(idx, phys) \
 		__set_fixmap(idx, phys, PAGE_KERNEL)