media: st-hva: Fix potential NULL pointer dereferences

When ctx_id >= HVA_MAX_INSTANCES in hva_hw_its_irq_thread() it tries to
access fields of ctx that is NULL at that point. The patch gets rid of
these accesses.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/sti/hva/hva-hw.c

@@ -130,8 +130,7 @@ static irqreturn_t hva_hw_its_irq_thread(int irq, void *arg)
 	ctx_id = (hva->sts_reg & 0xFF00) >> 8;
 	if (ctx_id >= HVA_MAX_INSTANCES) {
 		dev_err(dev, "%s     %s: bad context identifier: %d\n",
-			ctx->name, __func__, ctx_id);
-		ctx->hw_err = true;
+			HVA_PREFIX, __func__, ctx_id);
 		goto out;
 	}