crypto: sahara - set nb_[in|out]_sg as signed int

The two unsigned int variables nb_in_sg and nb_out_sg can be assigned
signed value (-EINVAL) from sg_nents_for_len().
Furthermore they are used only by dma_map_sg and dma_unmap_sg which wait
for an signed int, so they must be set as int.

Fixes: 6c2b74d4 ("crypto: sahara - check return value of sg_nents_for_len")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>