rockchip: rk8xx: allocate priv structure for driver

The rk8xx_priv structure need to allocate for driver, or else
it will cause data abort when CPU access it.

This is a bug fix for below patch set:
https://www.mail-archive.com/u-boot@lists.denx.de/msg247345.html

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/pmic/rk8xx.c b/drivers/power/pmic/rk8xx.c
index 09b9b54..eb3ec0f 100644
--- a/drivers/power/pmic/rk8xx.c
+++ b/drivers/power/pmic/rk8xx.c
@@ -111,6 +111,7 @@
 #if CONFIG_IS_ENABLED(PMIC_CHILDREN)
 	.bind = rk8xx_bind,
 #endif
+	.priv_auto_alloc_size   = sizeof(struct rk8xx_priv),
 	.probe = rk8xx_probe,
 	.ops = &rk8xx_ops,
 };