staging/lustre: don't compile procfs code when CONFIG_PROC_FS is off

The patch changes to conditionally compile procfs related source files.
This includes lproc_fid.c, lproc_fld.c, lproc_lov.c, lvfs_lib.c, lproc_mdc.c,
lproc_mgc.c, lprocfs_status.c, lproc_osc.c and sec_lproc.c.

There is a checkpatch warning about usage of simple_strtoul() in the patch.
But it needs to be fixed in a separate patch because it is not related to
CONFIG_PROC_FS breakage here.

Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>