staging/lustre: fix build error on BIGENDIAN machines

After merging the final tree, today's linux-next build (powerpc
allyesconfig) failed like this:

In file included from drivers/staging/lustre/include/linux/libcfs/libcfs.h:203:0,
                 from drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd.h:67,
                 from drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd.c:41:
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd.c: In function 'kiblnd_dev_need_failover':
drivers/staging/lustre/include/linux/libcfs/libcfs_debug.h:215:16: error: implicit declaration of function 'NIPQUAD' [-Werror=implicit-function-declaration]
  static struct libcfs_debug_msg_data msgdata;      \
                ^
NIPQUAD was deleted from kernel since v2.6.36 (commit cf4ca4874) but Lustre
certainly still wants it.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peng Tao <tao.peng@emc.com>