mkfs: always use new_diflags2 to initialize new inodes

mkfs: always use new_diflags2 to initialize new inodes

The new_diflags2 field that's set in the inode geometry represent
features that we want enabled for /all/ newly created inodes.
Unfortunately, mkfs doesn't do that because xfs_flags2diflags2 doesn't
read new_diflags2.  Change the new_diflags2 logic to match the kernel.

Without this fix, the root directory gets created without the
DIFLAG2_NREXT64 iflag set, but files created by a protofile /do/ have it
turned on.

This wasn't an issue with DIFLAG2_BIGTIME because xfs_trans_log_inode
quietly turns that on whenever possible.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>