p2p: fix buffer overflow on calling wpa_printf

SSID is not guaranteed to be a null-terminated string, it should
use wpa_ssid_txt to convert it to a null-terminated string.

Bug: 209554957
Test: atest VtsHalWifiSupplicantStaIfaceTargetTest \
            VtsHalWifiSupplicantStaNetworkTargetTest \
            VtsHalWifiSupplicantP2pIfaceTargetTest
Change-Id: I6aed10642b1d1f7da9ee9ef3ff726f20f69689ac
1 file changed