ARM: imx_v4_v5_defconfig: Build CONFIG_IMX_SDMA as module

Build CONFIG_IMX_SDMA as a module to allow the SDMA firmware be
retrieved after the rootfs is mounted.

This change aligns with the one already done for imx_v6_v7_defconfig
in commit 5a7374ec ("ARM: imx_v6_v7_defconfig: build imx sdma driver
as module").
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/configs/imx_v4_v5_defconfig

@@ -160,7 +160,7 @@ CONFIG_RTC_DRV_MC13XXX=y
 CONFIG_RTC_DRV_MXC=y
 CONFIG_DMADEVICES=y
 CONFIG_IMX_DMA=y
-CONFIG_IMX_SDMA=y
+CONFIG_IMX_SDMA=m
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_IIO=y
 CONFIG_FSL_MX25_ADC=y