powerpc: Remove empty giveup_altivec function on book3e CPUs

Use an empty inline instead of an empty function to implement
giveup_altivec on book3e CPUs, similar to flush_altivec_to_thread.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index caf82d0..2824609 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -21,7 +21,6 @@
 extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void enable_kernel_altivec(void);
-extern void giveup_altivec(struct task_struct *);
 extern void load_up_altivec(struct task_struct *);
 extern int emulate_altivec(struct pt_regs *);
 extern void __giveup_vsx(struct task_struct *);
@@ -40,10 +39,14 @@
 
 #ifdef CONFIG_ALTIVEC
 extern void flush_altivec_to_thread(struct task_struct *);
+extern void giveup_altivec(struct task_struct *);
 #else
 static inline void flush_altivec_to_thread(struct task_struct *t)
 {
 }
+static inline void giveup_altivec(struct task_struct *t)
+{
+}
 #endif
 
 #ifdef CONFIG_VSX