Nokia RX-51: Convert to CONFIG_DM_I2C

Use twl4030_i2c_read(), i2c_get_chip_for_busnum() and remove
CONFIG_SYS_I2C.

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/configs/nokia_rx51_defconfig b/configs/nokia_rx51_defconfig
index 1d35352..6310a12 100644
--- a/configs/nokia_rx51_defconfig
+++ b/configs/nokia_rx51_defconfig
@@ -60,3 +60,5 @@
 # CONFIG_VGA_AS_SINGLE_DEVICE is not set
 CONFIG_SPLASH_SCREEN=y
 # CONFIG_GZIP is not set
+CONFIG_DM=y
+CONFIG_DM_I2C=y