staging: lustre: simplify linux-prim.c

cfs_block_sigs() is never used.
cfs_clear_sigpending() is never used.
cfs_block_allsigs() is no longer used.

So those three functions can go.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>