Don't byte swap extents information in the inode

Don't byte swap extents information in the inode

Responsibility for byte swapping the extents information rests with
the low-level extent code, which translates the on-disk extents
information to the abstract extent format.  The on-disk format will
eventually get more complicated, in order to add support for 64-bit
block numbers, bit-compressed extents, etc.  So to avoid needing to
expose all of that complexity in swapfs.c, the in-memory contents of
i_blocks will not be byte-swapped and will be identical to the on-disk
format.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>