crypto: sahara - fix wait_for_completion_timeout() error handling

The sg lists are not unmapped in case of timeout errors. Fix this.

Fixes: 5a2bb93f ("crypto: sahara - add support for SHA1/256")
Fixes: 5de88752 ("crypto: sahara - Add driver for SAHARA2 accelerator.")
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>