sh: Handle shm_align_mask also for HAVE_ARCH_UNMAPPED_AREA_TOPDOWN.

Presently shm_align_mask is only looked at for the bottom up case, but we
still want this for proper colouring constraints in the topdown case.

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

arch/sh/include/asm/pgtable.h

@@ -154,6 +154,10 @@ extern void kmap_coherent_init(void);
 #define kmap_coherent_init()	do { } while (0)
 #endif
 
+/* arch/sh/mm/mmap.c */
+#define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+
 #include <asm-generic/pgtable.h>
 
 #endif /* __ASM_SH_PGTABLE_H */