ARM i.MX DMA: return gracefully on different socs

Code called from an initcall can be maybe called for
machines it's not intended for. So check for valid
machines and return gracefully if an incompatible machine
is found.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-imx/dma-v1.c

@@ -818,7 +818,7 @@ static int __init imx_dma_init(void)
 		imx_dmav1_baseaddr = MX27_IO_ADDRESS(MX27_DMA_BASE_ADDR);
 	else
 #endif
-		BUG();
+		return 0;
 
 	dma_clk = clk_get(NULL, "dma");
 	clk_enable(dma_clk);