crypto: chelsio - Fix potential NULL pointer dereferences

Add null checks on lookup_tid() return value in order to prevent
null pointer dereferences.

Addresses-Coverity-ID: 1467422 ("Dereference null return value")
Addresses-Coverity-ID: 1467443 ("Dereference null return value")
Addresses-Coverity-ID: 1467445 ("Dereference null return value")
Addresses-Coverity-ID: 1467449 ("Dereference null return value")
Fixes: cc35c88a

 ("crypto : chtls - CPL handler definition")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>