bcm43xxx: remove unuse function

I added a function that I didn't use when I upstream another patch. Delete it
apache#10709

Signed-off-by: zhanghongyu <zhanghongyu@xiaomi.com>

Author: xuxin930

drivers/wireless/ieee80211/bcm43xxx/bcmf_driver.c

@@ -419,34 +419,6 @@ int bcmf_driver_download_clm(FAR struct bcmf_dev_s *priv)
 #endif
 #endif /* CONFIG_IEEE80211_BROADCOM_HAVE_CLM */
 
-int bcmf_wl_set_pm(FAR struct bcmf_dev_s *priv, int mode)
-{
-  int interface = CHIP_STA_INTERFACE;
-  uint32_t out_len;
-  uint32_t value;
-  int ret = OK;
-
-  /* Set default power save mode */
-
-#ifdef CONFIG_IEEE80211_BROADCOM_LOWPOWER
-  if (priv->lp_mode != mode)
-#endif
-    {
-      out_len = 4;
-      value   = mode;
-      ret = bcmf_cdc_ioctl(priv, interface, true, WLC_SET_PM,
-                           (uint8_t *)&value, &out_len);
-#ifdef CONFIG_IEEE80211_BROADCOM_LOWPOWER
-      if (ret == OK)
-        {
-          priv->lp_mode = mode;
-        }
-#endif
-    }
-
-  return ret;
-}
-
 /****************************************************************************
  * Name: bcmf_wl_active
  ****************************************************************************/