Kconfig: convert CONFIG_SYS_I2C_LPC32XX

Convert the CONFIG_SYS_I2C_LPC32XX configuration symbol from an include
directive to a Kconfig value.

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/devkit3250_defconfig b/configs/devkit3250_defconfig
index 9ae70f7..c0354bc 100644
--- a/configs/devkit3250_defconfig
+++ b/configs/devkit3250_defconfig
@@ -38,6 +38,7 @@
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_VERSION_VARIABLE=y
+CONFIG_SYS_I2C_LPC32XX=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_NOR_FLASH=y