crypto: octeontx2 - add missing check for dma_map_single

Add check for dma_map_single() and return error if it fails in order
to avoid invalid dma address.

Fixes: e9297111 ("crypto: octeontx2 - add ctx_val workaround")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Reviewed-by: Bharat Bhushan <bbhushan2@marvell.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>