powerpc: Clean up copy_to/from_user for vsx and fpr

This merges and cleans up some of the ugly copy/to from user code
which is required for the new fpr and vsx layout in the thread_struct.

Also fixes some hard coded buffer sizes and removes a redundant
fpr_flush_to_thread.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h
index 77efb3d..28f4b9f 100644
--- a/arch/powerpc/kernel/signal.h
+++ b/arch/powerpc/kernel/signal.h
@@ -24,6 +24,16 @@
 			      siginfo_t *info, sigset_t *oldset,
 			      struct pt_regs *regs);
 
+extern unsigned long copy_fpr_to_user(void __user *to,
+				      struct task_struct *task);
+extern unsigned long copy_fpr_from_user(struct task_struct *task,
+					void __user *from);
+#ifdef CONFIG_VSX
+extern unsigned long copy_vsx_to_user(void __user *to,
+				      struct task_struct *task);
+extern unsigned long copy_vsx_from_user(struct task_struct *task,
+					void __user *from);
+#endif
 
 #ifdef CONFIG_PPC64