s390/cio: fix a memleak in css_alloc_subchannel

s390/cio: fix a memleak in css_alloc_subchannel

When dma_set_coherent_mask() fails, sch->lock has not been
freed, which is allocated in css_sch_create_locks(), leading
to a memleak.

Fixes: 4520a91a976e ("s390/cio: use dma helpers for setting masks")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Message-Id: <20230921071412.13806-1-dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/linux-s390/bd38baa8-7b9d-4d89-9422-7e943d626d6e@linux.ibm.com/
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>