Kconfig: Rename CONFIG_SPL_DMA_SUPPORT to CONFIG_SPL_DMA

Rename CONFIG_SPL_DMA_SUPPORT to CONFIG_SPL_DMA. This allows to use
macros such as CONFIG_IS_ENABLED() that allow conditional compilation of
code for SPL and U-Boot.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/am57xx_evm_defconfig b/configs/am57xx_evm_defconfig
index 0c6a2e9..6386157 100644
--- a/configs/am57xx_evm_defconfig
+++ b/configs/am57xx_evm_defconfig
@@ -23,7 +23,7 @@
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y
 CONFIG_SPL_SEPARATE_BSS=y
-CONFIG_SPL_DMA_SUPPORT=y
+CONFIG_SPL_DMA=y
 # CONFIG_SPL_NAND_SUPPORT is not set
 CONFIG_SPL_OS_BOOT=y
 CONFIG_SPL_SPI_LOAD=y