ARM: 9306/1: cacheflush: avoid __flush_anon_page() missing-prototype warning

The prototype for __flush_anon_page() is intentionally hidden
inside the flush_anon_page() inline function to prevent it from
being called from drivers.

When building with 'W=1', this causes a warning:

arch/arm/mm/flush.c:358:6: error: no previous prototype for '__flush_anon_page' [-Werror=missing-prototypes]

Work around this by adding a prototype directly next to the function
definition.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

arch/arm/mm/flush.c

@@ -354,6 +354,7 @@ EXPORT_SYMBOL(flush_dcache_page);
  *  memcpy() to/from page
  *  if written to page, flush_dcache_page()
  */
+void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr);
 void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
 {
 	unsigned long pfn;