dmaengine: Replace zero-length array with flexible-array

Documentation/process/deprecated.rst suggests that zero-length
and one-element arrays are deprecated, flexible-array members
should be used instead.

Signed-off-by: Chelsy Ratnawat <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/imx-sdma.c

···
 	/* End of v3 array */
 	union { s32 v3_end; s32 mcu_2_zqspi_addr; };
 	/* End of v4 array */
-	s32 v4_end[0];
+	s32 v4_end[];
 };
 
 /*