staging/lustre: drop CONFIG_BROKEN

This reverts commit 0ad1ea69

I didn't use git revert because it can not be done cleanly.
Hopefully it will be the last time we do it...

Cc: Stephen Rothwell <sfr@canb.auug.org.au>
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>