brcmfmac: support SAE authentication offload in AP mode

Firmware may have SAE 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 password material
in the nl80211 start AP command to offload the SAE authentication 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/20200817073316.33402-5-stanley.hsu@cypress.com