wifi: mwifiex: fix key_mgmt setting

bss_config->key_mgmt specifies the AKM suites that are usable in
hardware. This variable is set to specific values while iterating
over the advertised AKM suites. This means the final value of the
variable depends on the order of the entries in the AKM suites
array. Instead of setting the variable, just set the relevant bits
in the key_mgmt bit field to make us independent of the order of
entries.
This behaviour is derived from the downstream driver that does the
same.
Also, set bss_config->key_mgmt to zero explicitly right before the
loop. bss_config has been zero allocated by the caller already, but
do so again to save the reader from following the code path.

Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20240723-mwifiex-wpa-psk-sha256-v3-2-025168a91da1@pengutronix.de


Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20240805-mwifiex-wpa-psk-sha256-v4-2-e1eee80508e6@pengutronix.de