gfs2: Fix I_NEW check in gfs2_dinode_in

Patch 4a378d8a added a new check for I_NEW inodes, but unfortunately
it used the wrong variable, i_flags. This caused GFS2 to withdraw when
gfs2_lookup_by_inum needed to refresh an I_NEW inode. This patch switches
to use the correct variable, i_state.

Fixes: 4a378d8a ("gfs2: be careful with inode refresh")
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>