drm/msm/dpu: fix encoder irq wait skip

The irq_idx is unsigned so it cannot be lower than zero, better
to change the condition to check if it is equal with zero.
It could not cause any issue because a valid irq index starts from one.

Fixes: 5a9d5015 ("drm/msm/dpu: shift IRQ indices by 1")
Signed-off-by: Barnabás Czémán <trabarni@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/596853/
Link: https://lore.kernel.org/r/20240509-irq_wait-v2-1-b8b687b22cc4@gmail.comSigned-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

@@ -428,7 +428,7 @@ int dpu_encoder_helper_wait_for_irq(struct dpu_encoder_phys *phys_enc,
 		return -EWOULDBLOCK;
 	}
 
-	if (irq_idx < 0) {
+	if (irq_idx == 0) {
 		DRM_DEBUG_KMS("skip irq wait id=%u, callback=%ps\n",
 			      DRMID(phys_enc->parent), func);
 		return 0;