staging: rtl8188eu: avoid a null dereference on pmlmepriv

There is a check on pmlmepriv before dereferencing it when
vfree'ing pmlmepriv->free_bss_buf however the previous call
to rtw_free_mlme_priv_ie_data deferences pmlmepriv causing
a null pointer deference if it is null.  Avoid this by also
calling rtw_free_mlme_priv_ie_data if the pointer is non-null.

Detected by CoverityScan, CID#1230262 ("Dereference before null check")
Fixes: 7b464c9f ("staging: r8188eu: Add files for new driver - part 4")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/core/rtw_mlme.c

@@ -106,10 +106,10 @@ void rtw_free_mlme_priv_ie_data(struct mlme_priv *pmlmepriv)
 
 void rtw_free_mlme_priv(struct mlme_priv *pmlmepriv)
 {
-	rtw_free_mlme_priv_ie_data(pmlmepriv);
-
-	if (pmlmepriv)
+	if (pmlmepriv) {
+		rtw_free_mlme_priv_ie_data(pmlmepriv);
 		vfree(pmlmepriv->free_bss_buf);
+	}
 }
 
 struct wlan_network *_rtw_alloc_network(struct mlme_priv *pmlmepriv)