nvme-pci: fix out-of-bounds access in nvme_setup_descriptor_pools

nvme-pci: fix out-of-bounds access in nvme_setup_descriptor_pools

nvme_setup_descriptor_pools() indexes dev->descriptor_pools[] using the
numa_node forwarded from hctx->numa_node by its single caller,
nvme_init_hctx_common().  On a non-NUMA kernel hctx->numa_node is
NUMA_NO_NODE (-1).  Because the parameter was declared 'unsigned', the
value becomes UINT_MAX and the index walks off the array (sized to
nr_node_ids), faulting during nvme_alloc_ns() and leaving the namespace
without a /dev node.

Reproduces on any NVMe controller probed by a CONFIG_NUMA=n kernel:

  BUG: unable to handle page fault for address: ffff889101603d38
  RIP: 0010:nvme_init_hctx_common+0x5a/0x190 [nvme]
  Call Trace:
   nvme_init_hctx+0x10/0x20 [nvme]
   nvme_alloc_ns+0x9e/0xa10 [nvme_core]
   nvme_scan_ns+0x301/0x3b0 [nvme_core]
   nvme_scan_ns_async+0x23/0x30 [nvme_core]

Switch the parameter to int and fall back to node 0 when it is
NUMA_NO_NODE; node 0 is always present.

Fixes: d977506f8863 ("nvme-pci: make PRP list DMA pools per-NUMA-node")
Link: https://lore.kernel.org/r/20260309062840.2937858-2-iam@sung-woo.kim
Reported-by: Sung-woo Kim <iam@sung-woo.kim>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mateusz Nowicki <mateusz.nowicki@posteo.net>
Signed-off-by: Keith Busch <kbusch@kernel.org>