byteorder: move le32_add_cpu & friends from OCFS2 to core

This patchset moves le*_add_cpu and be*_add_cpu functions from OCFS2 to core
header (1st), converts ext3 filesystem to this API (2nd) and replaces XFS
different named functions with new ones (3rd).

There are many places where these functions will be useful.  Just look at:
grep -r 'cpu_to_[ble12346]*([ble12346]*_to_cpu.*[-+]' linux-src/ Patch for
ext3 is an example how conversions will probably look like.

This patch:

- move inline functions which add native byte order variable to
  little/big endian variable to core header
  * le16_add_cpu(__le16 *var, u16 val)
  * le32_add_cpu(__le32 *var, u32 val)
  * le64_add_cpu(__le64 *var, u64 val)
  * be32_add_cpu(__be32 *var, u32 val)
- add for completeness:
  * be16_add_cpu(__be16 *var, u16 val)
  * be64_add_cpu(__be64 *var, u64 val)

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Mark Fasheh <mark.fasheh@oracle.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Timothy Shimmin <tes@sgi.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>