[XFS] Fix xfs_ichgtime()s broken usage of I_SYNC

The recent I_LOCK->I_SYNC changes mistakenly changed xfs_ichgtime to look
at I_SYNC instead of I_LOCK. This was incorrect and prevents newly created
inodes from moving to the dirty list. Change this to the correct check
which is for I_NEW, not I_LOCK or I_SYNC so that behaviour is correct.

SGI-PV: 974225
SGI-Modid: xfs-linux-melb:xfs-kern:30204a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>