LU-1199 ldiskfs: Remove HAVE_{EXT4,JBD2}_JOURNAL_CALLBACK_{SET,ADD}

LU-1199 ldiskfs: Remove HAVE_{EXT4,JBD2}_JOURNAL_CALLBACK_{SET,ADD}

Lustre servers now only support kernels/ldiskfs with
{ext4,ldiskfs}_journal_callback_add().  Additionally, the
HAVE_EXT4_JOURNAL_CALLBACK_ADD define is not in the upstream
3.3 kernel where the ext4_journal_callback_add() patch landed.

Therefore we remove the HAVE_{LDISKFS,EXT4}_JOURNAL_CALLBACK_{SET,ADD}
checks and just assume that it is set.

Change-Id: I10cc79fcf07dd05a10ae83014f188c613ab1620c
Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Reviewed-on: http://review.whamcloud.com/5055
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>