Convert CONFIG_DMA_LPC32XX to Kconfig

This converts the following to Kconfig:
   CONFIG_DMA_LPC32XX

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/devkit3250_defconfig b/configs/devkit3250_defconfig
index 2d4d665..9c886a1 100644
--- a/configs/devkit3250_defconfig
+++ b/configs/devkit3250_defconfig
@@ -42,6 +42,7 @@
 CONFIG_VERSION_VARIABLE=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
+CONFIG_DMA_LPC32XX=y
 CONFIG_SYS_I2C_LPC32XX=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y