powerpc: convert to generic helpers for IPI function calls

This converts ppc to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

ppc loses the timeout functionality of smp_call_function_mask() with
this change, as the generic code does not provide that.

Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3934e26..852d40c 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -110,6 +110,7 @@
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_LMB
+	select USE_GENERIC_SMP_HELPERS if SMP
 
 config EARLY_PRINTK
 	bool