sh64: add missing #include <asm/fpu.h>'s

This patch fixes some compile errors due to missing save_fpu()
prototypes on sh64 caused by
commit 9bbafce2eec190ef7e44b0eb1095ba17ce6ad3af
(sh: Fix occasional FPU register corruption under preempt).

Signed-off-by: Adrian Bunk <adrian.bunk@movial.fi>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 046999b..0283d81 100644
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -28,6 +28,7 @@
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/mmu_context.h>
+#include <asm/fpu.h>
 
 struct task_struct *last_task_used_math = NULL;