crypto: chelsio - remove redundant assignments to reqctx and dst_size

Pointer reqctx is assigned the same value twice, once on initialization
and again a few statements later, remove the second redundant assignment.
Variable dst_size is assigned but it is never read, so the variable is
redundant and can be removed. Cleans up clang warnings:

drivers/crypto/chelsio/chcr_algo.c:156:29: warning: Value stored to
'reqctx' during its initialization is never read
drivers/crypto/chelsio/chcr_algo.c:2020:2: warning: Value stored to
'dst_size' is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>