brcmfmac: support 4-way handshake offloading for WPA/WPA2-PSK in AP mode

Firmware may have authenticator code built-in. This is detected by the
driver and indicated in the wiphy features flags. User space can use
this flag to determine whether or not to provide the pre-shared key
material in the nl80211 start AP command to offload the 4-way handshake
in AP mode.

Signed-off-by: Chung-Hsien Hsu <stanley.hsu@cypress.com>
Signed-off-by: Chi-Hsien Lin <chi-hsien.lin@cypress.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200817073316.33402-3-stanley.hsu@cypress.com