drm/panthor: Cleanup unused variable 'cookie'

Commit 962f88b9 ("drm/panthor: Drop the dev_enter/exit() sections in
_irq_suspend/resume()") removed the code that used the 'cookie' variable
but left the declaration in place. Remove it.

Fixes: 962f88b9 ("drm/panthor: Drop the dev_enter/exit() sections in _irq_suspend/resume()")
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402215423.360341-1-liviu.dudau@arm.com

drivers/gpu/drm/panthor/panthor_device.h

@@ -323,8 +323,6 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
 												\
 static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)			\
 {												\
-	int cookie;										\
-												\
 	pirq->mask = 0;										\
 	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, 0);					\
 	synchronize_irq(pirq->irq);								\
@@ -333,8 +331,6 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
 												\
 static inline void panthor_ ## __name ## _irq_resume(struct panthor_irq *pirq, u32 mask)	\
 {												\
-	int cookie;										\
-												\
 	atomic_set(&pirq->suspended, false);							\
 	pirq->mask = mask;									\
 	gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, mask);				\