fs: fix function param name in kernel-doc

Fix function parameter name in kernel-doc:

Warning(linux-2.6.28-git5//fs/block_dev.c:1272): No description found for parameter 'pathname'
Warning(linux-2.6.28-git5//fs/block_dev.c:1272): Excess function parameter 'path' description in 'lookup_bdev'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/block_dev.c

@@ -1262,7 +1262,7 @@ EXPORT_SYMBOL(ioctl_by_bdev);
 
 /**
  * lookup_bdev  - lookup a struct block_device by name
- * @path:	special file representing the block device
+ * @pathname:	special file representing the block device
  *
  * Get a reference to the blockdevice at @pathname in the current
  * namespace if possible and return it.  Return ERR_PTR(error)