dmaengine: dw-axi-dmac: remove redundant null check on desc

The pointer desc is being null checked twice, the second null check
is redundant because desc has not been re-assigned between the
checks. Remove the redundant second null check on desc.

Fixes: ef6fb2d6f1ab ("dmaengine: dw-axi-dmac: simplify descriptor management")
Signed-off-by: Colin Ian King <[e-mail]>
Tested-by: Sia Jee Heng <[e-mail]>
Reviewed-by: Sia Jee Heng <[e-mail]>
Addresses-Coverity: ("Logically dead code")
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c

···
 		num++;
 	}
 
-	/* Total len of src/dest sg == 0, so no descriptor were allocated */
-	if (unlikely(!desc))
-		return NULL;
-
 	/* Set end-of-link to the last link descriptor of list */
 	set_desc_last(&desc->hw_desc[num - 1]);
 	/* Managed transfer list */