brcmfmac: Fix WEP configuration for AP mode.

When a device is configured for AP mode and it is configured for
WEP then the keys are plumbed first, followed by AP configuration.
During configuration a down command is given to the firmware which
will clear the configured keys. This patch reprograms the WEP keys
after AP has been brought up.

Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>