sh: Calculate shm alignment at runtime.

Set the SHM alignment at runtime, based off of probed cache desc.
Optimize get_unmapped_area() to only colour align shared mappings.

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

include/asm-sh/page.h

@@ -44,6 +44,8 @@
 extern void (*clear_page)(void *to);
 extern void (*copy_page)(void *to, void *from);
 
+extern unsigned long shm_align_mask;
+
 #ifdef CONFIG_MMU
 extern void clear_page_slow(void *to);
 extern void copy_page_slow(void *to, void *from);