net/failsafe: fix error string after ownership call
net/failsafe: fix error string after ownership call

Ownership API returns a negative value, strerror expects a valid errno
value, thus positive.

Coverity issue: 260401
Fixes: dcd0c9c32b8d ("net/failsafe: use ownership mechanism for slaves")

Signed-off-by: Gaetan Rivet <a6b9f1aecd7707f01344f211143eb3bcaeb0c5c3@6wind.com>

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