dmaengine: pl330: Initialize pl330 for pl330_prep_dma_memcpy after NULL check of pch

Currently pch pointer is already dereferenced before NULL check
and thus we are getting below warning:
warn: variable dereferenced before check 'pch'

So initialize struct pl330_dmac *pl330 after NULL check
of dma_pl330_chan *pch.

Signed-off-by: Maninder Singh <[e-mail]>
Reviewed-by: Vaneet Narang <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/pl330.c

···
 {
 	struct dma_pl330_desc *desc;
 	struct dma_pl330_chan *pch = to_pchan(chan);
-	struct pl330_dmac *pl330 = pch->dmac;
+	struct pl330_dmac *pl330;
 	int burst;
 
 	if (unlikely(!pch || !len))
 		return NULL;
+
+	pl330 = pch->dmac;
 
 	desc = __pl330_prep_dma_memcpy(pch, dst, src, len);
 	if (!desc)