partx: don't report ENXIO as error on -d

partx: don't report ENXIO as error on -d

The errno ENXIO should be ignored, unfortunately the current code uses
variable 'rc' for ioctl return code as well as for final del_parts()
return value. So, failed ioctl (which should be ignored) affects all
del_parts() status.

  # modprobe scsi_debug dev_size_mb=100
  # partx  -d --nr 1-1024 /dev/sdc; echo $?
  1

The device dos not contains any partitions, so 0 return code is
expected in this case.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1739179
Signed-off-by: Karel Zak <kzak@redhat.com>