media: venus: dec: Handle the case where find_format fails

Debugging the decoder on msm8916 I noticed the vdec probe was crashing if
the fmt pointer was NULL.

A similar fix from Colin Ian King found by Coverity was implemented for the
encoder. Implement the same fix on the decoder.

Fixes: 7472c1c6 ("[media] media: venus: vdec: add video decoder files")
Cc: stable@vger.kernel.org  # v4.13+
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/platform/qcom/venus/vdec.c

@@ -183,6 +183,8 @@ vdec_try_fmt_common(struct venus_inst *inst, struct v4l2_format *f)
 		else
 			return NULL;
 		fmt = find_format(inst, pixmp->pixelformat, f->type);
+		if (!fmt)
+			return NULL;
 	}
 
 	pixmp->width = clamp(pixmp->width, frame_width_min(inst),