12181 zvol swap tests should avoid grep -w

*** 24,33 ****
--- 24,34 ----
  # Use is subject to license terms.
  #
  
  #
  # Copyright (c) 2013, 2016 by Delphix. All rights reserved.
+ # Copyright 2020 Joyent, Inc.
  #
  
  . $STF_SUITE/include/libtest.shlib
  . $STF_SUITE/tests/functional/zvol/zvol.cfg
  
*** 131,138 ****
          if [[ -z $device ]] ; then
                  log_note "No device specified."
                  return 1
          fi
  
!         swap -l | grep -w $device > /dev/null 2>&1
          return $?
  }
--- 132,140 ----
          if [[ -z $device ]] ; then
                  log_note "No device specified."
                  return 1
          fi
  
!         swap -l | awk 'NR > 1 { print $1 }' | \
!             grep "^$device\$" > /dev/null 2>&1
          return $?
  }