lib/mpi: headers cleanup

lib/mpi: headers cleanup

MPI headers contain definitions for huge number of non-existing
functions.

Most part of these functions was removed in 2012 by Dmitry Kasatkin
 - 7cf4206a99d1 ("Remove unused code from MPI library")
 - 9e235dcaf4f6 ("Revert "crypto: GnuPG based MPI lib - additional ...")
 - bc95eeadf5c6 ("lib/mpi: removed unused functions")
however headers wwere not updated properly.

Also I deleted some unused macros.

Link: http://lkml.kernel.org/r/fb2fc1ef-1185-f0a3-d8d0-173d2f97bbaf@virtuozzo.com
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>