skd: fix function prototype

Building with W=1 shows a harmless warning for the skd driver:

drivers/block/skd_main.c:2959:1: error: ‘static’ is not at beginning of declaration [-Werror=old-style-declaration]

This changes the prototype to the expected formatting.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/skd_main.c

@@ -2945,8 +2945,8 @@ static void skd_completion_worker(struct work_struct *work)
 
 static void skd_isr_msg_from_dev(struct skd_device *skdev);
 
-irqreturn_t
-static skd_isr(int irq, void *ptr)
+static irqreturn_t
+skd_isr(int irq, void *ptr)
 {
 	struct skd_device *skdev;
 	u32 intstat;