m68knommu: remove unused kernel_set_cachemode()

None of the m68knommu platforms will ever use kernel_set_cachemode().
And it is specific to a couple of m68k devices. So remove it.
Signed-off-by: NGreg Ungerer <gerg@uclinux.org>

arch/m68k/mm/kmap_no.c

@@ -35,11 +35,3 @@ void iounmap(void *addr)
 {
 }
 
-/*
- * Set new cache mode for some kernel address space.
- * The caller must push data for that range itself, if such data may already
- * be in the cache.
- */
-void kernel_set_cachemode(void *addr, unsigned long size, int cmode)
-{
-}