powerpc: Remove the empty giveup_fpu() function on 32bit kernel

Instead of implementing an empty giveup_fpu() function for each
32bit processor type, replace them with an unique empty inline
function.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/head_40x.S

@@ -822,14 +822,6 @@ finish_tlb_load:
 	rfi			/* Should sync shadow TLBs */
 	b	.		/* prevent prefetch past rfi */
 
-/* extern void giveup_fpu(struct task_struct *prev)
- *
- * The PowerPC 4xx family of processors do not have an FPU, so this just
- * returns.
- */
-_ENTRY(giveup_fpu)
-	blr
-
 /* This is where the main kernel code starts.
  */
 start_here: