sh: Don't export flush_dcache_all().

flush_dcache_all() is used internally by the SH-4 cache code, it is not
part of the exported cache API, so make it static and don't export it.

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

arch/sh/include/cpu-sh4/cpu/cacheflush.h

@@ -17,7 +17,6 @@
  *  so we need them.
  */
 void flush_cache_all(void);
-void flush_dcache_all(void);
 void flush_cache_mm(struct mm_struct *mm);
 #define flush_cache_dup_mm(mm) flush_cache_mm(mm)
 void flush_cache_range(struct vm_area_struct *vma, unsigned long start,