It is possible that wlantest has not yet created the BSS entry in all
cases, so interpret failures (no BSS entry being the most likely cause)
as zero counters. Similarly, ignore clear_bss_counters errors since they
are most likely reporting that the BSS was not found and as such, there
was no need to clear the counters anyway.
Signed-hostap: Jouni Malinen <j@w1.fi>