mtd: Remove redundant mutex from mtd_blkdevs.c

In commit 2a48fc0ab24241755dc93bfd4f01d68efab47f5a ('block: autoconvert
trivial BKL users to private mutex'), Arnd replaced the BKL usage with a
mutex. However, Maxim has already provided a better fix in commit
480792b7bf188c29b8d4b10fee65c3a06ec5dbf7 ('mtd: blktrans: kill BKL'),
which was simply to remove the BKL without replacing it — since he'd
already made it do all necessary locking for itself.

Signed-off-by: David Woodhouse <[e-mail]>

drivers/mtd/mtd_blkdevs.c

···
 
 #include "mtdcore.h"
 
-static DEFINE_MUTEX(mtd_blkdevs_mutex);
 static LIST_HEAD(blktrans_majors);
 static DEFINE_MUTEX(blktrans_ref_mutex);
 
···
 	if (!dev)
 		return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (dev->open++)
···
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	return ret;
 }
 
···
 	if (!dev)
 		return ret;
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (--dev->open)
···
 unlock:
 	mutex_unlock(&dev->lock);
 	blktrans_dev_put(dev);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	return ret;
 }
 
···
 	if (!dev)
 		return ret;
 
-	mutex_lock(&mtd_blkdevs_mutex);
 	mutex_lock(&dev->lock);
 
 	if (!dev->mtd)
···
 	}
 unlock:
 	mutex_unlock(&dev->lock);
-	mutex_unlock(&mtd_blkdevs_mutex);
 	blktrans_dev_put(dev);
 	return ret;
 }