LU-14151 gss: use skcipher when sync_skcipher not available

LU-14151 gss: use skcipher when sync_skcipher not available

Linux 4.2 introduced support for skcipher in commit
7a7ffe65c8c5 crypto: skcipher - Add top-level skcipher interface

Based on the existence of crypto_alloc_skcipher, use the skcipher API
instead of the blkcipher API, in case the sync_skcipher API is not
available.

Test-Parameters: clientdistro=el8.2 env=SHARED_KEY=true,SK_FLAVOR=skpi mdscount=2 mdtcount=4 osscount=1 ostcount=8 clientcount=2 testlist=sanity
Test-Parameters: clientdistro=el7.8 env=SHARED_KEY=true,SK_FLAVOR=skpi mdscount=2 mdtcount=4 osscount=1 ostcount=8 clientcount=2 testlist=sanity
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I4e62cd5c8219a215c5528f81d525c054215073e3
Reviewed-on: https://review.whamcloud.com/40768
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>