staging: ozwpan: prevent overflow in oz_cdev_write()

We need to check "count" so we don't overflow the ei->data buffer.

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
static int oz_cdev_open(struct inode *inode, struct file *filp)
{
	struct oz_cdev *dev = container_of(inode->i_cdev, struct oz_cdev, cdev);

	oz_dbg(ON, "major = %d minor = %d\n", imajor(inode), iminor(inode));

	filp->private_data = dev;
	return 0;
}

static int oz_cdev_open(struct inode *inode, struct file *filp)
{
	struct oz_cdev *dev = container_of(inode->i_cdev, struct oz_cdev, cdev);

	oz_dbg(ON, "major = %d minor = %d\n", imajor(inode), iminor(inode));

	filp->private_data = dev;
	return 0;
}
