drm: adp: Remove pointless irq_lock spin lock

Interrupt handlers run with interrupts disabled so it is not necessary
to protect them against reentrancy.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Janne Grunau <j@jannau.net>
Link: https://lore.kernel.org/r/20250428-drm_adp_fixes-v2-4-912e081e55d8@jannau.net
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

Author: jannau

drivers/gpu/drm/adp/adp_drv.c

@@ -121,7 +121,6 @@ struct adp_drv_private {
 	dma_addr_t mask_iova;
 	int be_irq;
 	int fe_irq;
-	spinlock_t irq_lock;
 	struct drm_pending_vblank_event *event;
 };
 
@@ -490,8 +489,6 @@ static irqreturn_t adp_fe_irq(int irq, void *arg)
 	u32 int_status;
 	u32 int_ctl;
 
-	spin_lock(&adp->irq_lock);
-
 	int_status = readl(adp->fe + ADP_INT_STATUS);
 	if (int_status & ADP_INT_STATUS_VBLANK) {
 		drm_crtc_handle_vblank(&adp->crtc);
@@ -509,7 +506,6 @@ static irqreturn_t adp_fe_irq(int irq, void *arg)
 
 	writel(int_status, adp->fe + ADP_INT_STATUS);
 
-	spin_unlock(&adp->irq_lock);
 
 	return IRQ_HANDLED;
 }
@@ -574,8 +570,6 @@ static int adp_probe(struct platform_device *pdev)
 	if (IS_ERR(adp))
 		return PTR_ERR(adp);
 
-	spin_lock_init(&adp->irq_lock);
-
 	dev_set_drvdata(&pdev->dev, &adp->drm);
 
 	err = adp_parse_of(pdev, adp);