staging: lustre: discard cfs_block_sigsinv()

cfs_block_sigsinv() and cfs_restore_sigs() are simple
wrappers which save a couple of line of code and
hurt readability for people not familiar with them.
They aren't used often enough to be worthwhile,
so discard them and open-code the functionality.

The sigorsets() call isn't needed as or-ing with current->blocked is
exactly what sigprocmask(SIG_BLOCK) does.

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