nvme-cli: fix connecting failure due to invalid uuid format of hostid

nvme-cli: fix connecting failure due to invalid uuid format of hostid

When we connect or discover a target with --hostid option via the
/etc/nvme/hostid file, we fails this operation because the hostid
is only 35 not 36 bytes which doesn't pass the uuid checking in the
kernel.The last character is overridden with null bytes because fgets
reads at most one less than sizeof of buffer characters.

Signed-off-by: Guan Junxiong <guanjunxiong@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>