nvmeof-mp/001: fix failure when CONFIG_NVME_HWMON enabled

nvmeof-mp/001: fix failure when CONFIG_NVME_HWMON enabled

skip checking ng0n1/hwmon5 in count_devices

$ use_siw=1  ./check nvmeof-mp/001
nvmeof-mp/001 (Log in and log out)                           [failed]
    runtime  3.695s  ...  4.002s
    --- tests/nvmeof-mp/001.out	2021-09-12 05:35:17.866892187 -0400
    +++ /root/blktests/results/nodev/nvmeof-mp/001.out.bad	2021-09-12 06:49:25.621880616 -0400
    @@ -1,3 +1,3 @@
     Configured NVMe target driver
    -count_devices(): 1 <> 1
    +count_devices(): 3 <> 1
     Passed
$ ls -l /sys/class/nvme-fabrics/ctl/*/*/device
lrwxrwxrwx. 1 root root 0 Sep 12 06:49 /sys/class/nvme-fabrics/ctl/nvme0/hwmon5/device -> ../../nvme0
lrwxrwxrwx. 1 root root 0 Sep 12 06:49 /sys/class/nvme-fabrics/ctl/nvme0/ng0n1/device -> ../../nvme0
lrwxrwxrwx. 1 root root 0 Sep 12 06:49 /sys/class/nvme-fabrics/ctl/nvme0/nvme0n1/device -> ../../nvme0

Signed-off-by: Yi Zhang <yi.zhang@redhat.com>