allwinner: Use RSB for the PMIC connection on H6

RSB is faster and more efficient, and it has a simpler driver. As long
as the PMIC is returned to I2C mode after use, the rich OS can later use
either bus.

Change-Id: I0c5f32e88a090c8c5cccb81bd24596b301ab9da7
Signed-off-by: Samuel Holland <samuel@sholland.org>
diff --git a/plat/allwinner/sun50i_h6/platform.mk b/plat/allwinner/sun50i_h6/platform.mk
index 4ecc57c..1c98919 100644
--- a/plat/allwinner/sun50i_h6/platform.mk
+++ b/plat/allwinner/sun50i_h6/platform.mk
@@ -8,4 +8,4 @@
 include plat/allwinner/common/allwinner-common.mk
 
 BL31_SOURCES		+=	drivers/allwinner/axp/axp805.c		\
-				drivers/mentor/i2c/mi2cv.c
+				drivers/allwinner/sunxi_rsb.c