Convert CONFIG_SPL_I2C_SUPPORT to Kconfig

Move this option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/A10-OLinuXino-Lime_defconfig b/configs/A10-OLinuXino-Lime_defconfig
index 80757bc..04b720d 100644
--- a/configs/A10-OLinuXino-Lime_defconfig
+++ b/configs/A10-OLinuXino-Lime_defconfig
@@ -1,5 +1,6 @@
 CONFIG_ARM=y
 CONFIG_ARCH_SUNXI=y
+CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_MACH_SUN4I=y
 CONFIG_DRAM_CLK=480
 CONFIG_DRAM_EMR1=4