s390/pci: don't set failed sg dma_address to DMA_MAPPING_ERROR

s390/pci: don't set failed sg dma_address to DMA_MAPPING_ERROR

Setting the ->dma_address to DMA_MAPPING_ERROR is not part of
the ->map_sg calling convention, so remove it.

Link: https://lore.kernel.org/linux-mips/20210716063241.GC13345@lst.de/
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>