hostapd: initialize first BSS radio_mask during driver init

hostapd: initialize first BSS radio_mask during driver init

Secondary BSSes inherit the alloc value which bypasses
NL80211_ATTR_VIF_RADIO_MASK in nl80211_create_iface() and causes the
kernel to default new interfaces to all radios.

The ucode bss_create fallback fails to correct this because
the interface is already UP.. the kernel rejects SET_INTERFACE with
-EBUSY.

Signed-off-by: Chad Monroe <chad@monroe.io>
(cherry picked from commit 50d3d287e4cfafd5e0cf727d55472df7bd0e1c0c)