ANDROID: GKI: cfg80211: add ABI changes for CONFIG_NL80211_TESTMODE

This change adds the ABI requirements for CONFIG_NL80211_TESTMODE. This
allows vendors to enable the config without breaking ABI compatibility.

Bug: 159371702
Bug: 159417269
Change-Id: I6f8968d3be0c5e58bf921a93ae421882078edca9
Signed-off-by: Will McVicker <willmcvicker@google.com>