doc: fix igb_uio parameter in ntb guide
doc: fix igb_uio parameter in ntb guide

In prerequisites of ntb guide, the correct flag when loading igb_uio
module should be `wc_activate=1`, not `wc_active=1`.

Fixes: 11b5c7daf019 ("raw/ntb: add enqueue and dequeue functions")
Cc: stable@dpdk.org

Signed-off-by: Xiaoyun Li <151cc00bdba86cfa2ecfc39aaa98def8f092d9d8@intel.com>
Acked-by: Jingjing Wu <64d28b617c3b4840f5ded1bfa611cba7fadfe5c7@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk