drm/mediatek: Fix platform_get_irq() error checking

The platform_get_irq() function returns negative error codes on failure
and positive non-zero IRQ numbers on success. It never returns NULL. Fix
the error checking to look for negatives, and change "hdmi->irq" from
unsigned int to just int.

Fixes: 8d0f79886273 ("drm/mediatek: Introduce HDMI/DDC v2 for MT8195/MT8188")
Signed-off-by: Dan Carpenter <[e-mail]>
https://patchwork.kernel.org/project/dri-devel/patch/[e-mail]/
Signed-off-by: Chun-Kuang Hu <[e-mail]>

drivers/gpu/drm/mediatek/mtk_hdmi_common.c

···
 		return dev_err_probe(dev, ret, "Failed to get clocks\n");
 
 	hdmi->irq = platform_get_irq(pdev, 0);
-	if (!hdmi->irq)
+	if (hdmi->irq < 0)
 		return hdmi->irq;
 
 	hdmi->regs = device_node_to_regmap(dev->of_node);

drivers/gpu/drm/mediatek/mtk_hdmi_common.h

···
 	bool audio_enable;
 	bool powered;
 	bool enabled;
-	unsigned int irq;
+	int irq;
 	enum hdmi_hpd_state hpd;
 	hdmi_codec_plugged_cb plugged_cb;
 	struct device *codec_dev;