powerpc: Do not call prink when CONFIG_PRINTK is not defined

When printk() is disabled (CONFIG_PRINTK) at menu item
 General setup
 -> Configure standard kernel features (for small systems)
    -> Enable support for printk
then there should be no printk() calls at all.
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/head_fsl_booke.S

@@ -884,13 +884,17 @@ KernelSPE:
 	lwz	r3,_MSR(r1)
 	oris	r3,r3,MSR_SPE@h
 	stw	r3,_MSR(r1)	/* enable use of SPE after return */
+#ifdef CONFIG_PRINTK
 	lis	r3,87f@h
 	ori	r3,r3,87f@l
 	mr	r4,r2		/* current */
 	lwz	r5,_NIP(r1)
 	bl	printk
+#endif
 	b	ret_from_except
+#ifdef CONFIG_PRINTK
 87:	.string	"SPE used in kernel  (task=%p, pc=%x)  \n"
+#endif
 	.align	4,0
 
 #endif /* CONFIG_SPE */