crypto: hisilicon - init curr_sgl_dma to fix compile warning

Just init curr_sgl_dma = 0 to avoid compile warning.

Fixes: dfed0098 ("crypto: hisilicon - add hardware SGL support")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>