staging: lustre: make include/linux/libcfs/linux/linux-crypto.h private

There are only 2 functions that are actually called from it, so move it
to the local place where it is needed, no need for it to be "global" for
the rest of lustre to see it.

Also remove the unneeded EXPORT_SYMBOL() markings for these functions,
as no one else calls them.

Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: hpdd-discuss <hpdd-discuss@lists.01.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>