block, char_dev: Use correct format specifier for unsigned ints

register_blkdev() and __register_chrdev_region() treat the major
number as an unsigned int. So print it the same way to avoid
absurd error statements such as:
"... major requested (-1) is greater than the maximum (511) ..."
(and also fix off-by-one bugs in the error prints).

While at it, also update the comment describing register_blkdev().

Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 33c9385..a279c58 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -121,8 +121,8 @@
 	}
 
 	if (major >= CHRDEV_MAJOR_MAX) {
-		pr_err("CHRDEV \"%s\" major requested (%d) is greater than the maximum (%d)\n",
-		       name, major, CHRDEV_MAJOR_MAX);
+		pr_err("CHRDEV \"%s\" major requested (%u) is greater than the maximum (%u)\n",
+		       name, major, CHRDEV_MAJOR_MAX-1);
 		ret = -EINVAL;
 		goto out;
 	}