staging: brcm80211: return error code to mac80211 for 40MHz channels

When mac80211 attempts to configure the driver for 40MHz channel it
will return an error code -EIO as this is not yet supported.
Reviewed-by: NRoland Vossen <rvossen@broadcom.com>
Reviewed-by: NBrett Rudley <brudley@broadcom.com>
Reviewed-by: NHenry Ptasinski <henryp@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/brcm80211/brcmsmac/wl_mac80211.c

@@ -246,6 +246,7 @@ ieee_set_channel(struct ieee80211_hw *hw, struct ieee80211_channel *chan,
 	case NL80211_CHAN_HT40MINUS:
 	case NL80211_CHAN_HT40PLUS:
 		WL_ERROR("%s: Need to implement 40 Mhz Channels!\n", __func__);
+		err = 1;
 		break;
 	}