brcmsmac: make brcms_c_set_mac() void

Fix the following coccicheck warning:

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:3773:5-8:
Unneeded variable: "err". Return "0" on line 3781
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200410090817.26883-1-yanaijie@huawei.com

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c

@@ -3768,17 +3768,14 @@ static void brcms_c_set_ps_ctrl(struct brcms_c_info *wlc)
  * Write this BSS config's MAC address to core.
  * Updates RXE match engine.
  */
-static int brcms_c_set_mac(struct brcms_bss_cfg *bsscfg)
+static void brcms_c_set_mac(struct brcms_bss_cfg *bsscfg)
 {
-	int err = 0;
 	struct brcms_c_info *wlc = bsscfg->wlc;
 
 	/* enter the MAC addr into the RXE match registers */
 	brcms_c_set_addrmatch(wlc, RCM_MAC_OFFSET, wlc->pub->cur_etheraddr);
 
 	brcms_c_ampdu_macaddr_upd(wlc);
-
-	return err;
 }
 
 /* Write the BSS config's BSSID address to core (set_bssid in d11procs.tcl).