media: omap3isp: mark isp_isr_dbg as __maybe_unused

This function is only used for debugging purposes. When DEBUG
is disabled, it becomes unused, causing a clang warning with W=1.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/omap3isp/isp.c

@@ -476,7 +476,8 @@ void omap3isp_hist_dma_done(struct isp_device *isp)
 	}
 }
 
-static inline void isp_isr_dbg(struct isp_device *isp, u32 irqstatus)
+static inline void __maybe_unused isp_isr_dbg(struct isp_device *isp,
+					      u32 irqstatus)
 {
 	static const char *name[] = {
 		"CSIA_IRQ",