crypto: af_alg - fixed style error in af_alg.c

Fixed style error identified by checkpatch.

ERROR: space required before the open parenthesis '('
+               switch(cmsg->cmsg_type) {

Signed-off-by: Joshua I. James <joshua@cybercrimetech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>