pnfs/flexfiles: Fix memory leak in nfs4_ff_alloc_deviceid_node()

pnfs/flexfiles: Fix memory leak in nfs4_ff_alloc_deviceid_node()

In nfs4_ff_alloc_deviceid_node(), if the allocation for ds_versions fails,
the function jumps to the out_scratch label without freeing the already
allocated dsaddrs list, leading to a memory leak.

Fix this by jumping to the out_err_drain_dsaddrs label, which properly
frees the dsaddrs list before cleaning up other resources.

Fixes: d67ae825a59d6 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>