HSI: omap_ssi_port: Fix dma_map_sg error check

[ Upstream commit 551e325bbd3fb8b5a686ac1e6cf76e5641461cf2 ]

dma_map_sg return 0 on error, in case of error return -EIO
to caller.

Cc: Sebastian Reichel <sre@kernel.org>
Cc: linux-kernel@vger.kernel.org (open list)
Fixes: b209e047 ("HSI: Introduce OMAP SSI driver")
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>