ARM: sun6i: Use CPU_METHOD_OF_DECLARE

CPU_METHOD_OF_DECLARE allows to bind the smp_ops to a set of cpus through the
enable-method property, instead of relying on the machine to define it. Switch
to it to get closer to an empty machine.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/arch/arm/mach-sunxi/platsmp.c b/arch/arm/mach-sunxi/platsmp.c
index 0c7dbce..828f211 100644
--- a/arch/arm/mach-sunxi/platsmp.c
+++ b/arch/arm/mach-sunxi/platsmp.c
@@ -122,3 +122,4 @@
 	.smp_prepare_cpus	= sun6i_smp_prepare_cpus,
 	.smp_boot_secondary	= sun6i_smp_boot_secondary,
 };
+CPU_METHOD_OF_DECLARE(sun6i_smp, "allwinner,sun6i-a31", &sun6i_smp_ops);