i2c: Rename SPL/TPL_I2C_SUPPORT to I2C

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/configs/am335x_shc_netboot_defconfig b/configs/am335x_shc_netboot_defconfig
index 6451799..43fef20 100644
--- a/configs/am335x_shc_netboot_defconfig
+++ b/configs/am335x_shc_netboot_defconfig
@@ -29,7 +29,7 @@
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SPL_ENV_SUPPORT=y
 CONFIG_SPL_FS_EXT4=y
-CONFIG_SPL_I2C_SUPPORT=y
+CONFIG_SPL_I2C=y
 # CONFIG_SPL_NAND_SUPPORT is not set
 CONFIG_SPL_OS_BOOT=y
 CONFIG_SPL_POWER=y