arm64: defconfig: build imx-sdma as a module

[ Upstream commit e95622289f ]

This avoids firmware load error and sysfs fallback reported as follows:

[    0.199448] imx-sdma 302c0000.dma-controller: Direct firmware load
 for imx/sdma/sdma-imx7d.bin failed with error -2
[    0.199487] imx-sdma 302c0000.dma-controller: Falling back to sysfs
 fallback for: imx/sdma/sdma-imx7d.bin

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/arm64/configs/defconfig

@@ -921,7 +921,7 @@ CONFIG_DMADEVICES=y
 CONFIG_DMA_BCM2835=y
 CONFIG_DMA_SUN6I=m
 CONFIG_FSL_EDMA=y
-CONFIG_IMX_SDMA=y
+CONFIG_IMX_SDMA=m
 CONFIG_K3_DMA=y
 CONFIG_MV_XOR=y
 CONFIG_MV_XOR_V2=y