powerpc: Fix SMP issues with ppc64le ABIv2

There is no need to put a function descriptor in
__secondary_hold_spinloop. Use ppc_function_entry to get the
instruction address and put it in __secondary_hold_spinloop instead.

Also fix an issue where we assumed cur_cpu_spec held a function
descriptor.

Signed-off-by: Anton Blanchard <anton@samba.org>

arch/powerpc/kernel/setup_64.c

@@ -341,7 +341,7 @@ void smp_release_cpus(void)
 
 	ptr  = (unsigned long *)((unsigned long)&__secondary_hold_spinloop
 			- PHYSICAL_START);
-	*ptr = __pa(generic_secondary_smp_init);
+	*ptr = ppc_function_entry(generic_secondary_smp_init);
 
 	/* And wait a bit for them to catch up */
 	for (i = 0; i < 100000; i++) {