staging: rtl8188eu: fix potential leak in rtw_wx_set_enc_ext()

Function rtw_wx_set_enc_ext() dynamically allocates a temporary buffer that
is not freed in all error paths. Use a centralized exit path and make sure
that all memory is freed correctly. Detected by Coverity - CID 1077712.
Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/ioctl_linux.c

@@ -2097,7 +2097,8 @@ static int rtw_wx_set_enc_ext(struct net_device *dev,
 		alg_name = "CCMP";
 		break;
 	default:
-		return -1;
+		ret = -1;
+		goto exit;
 	}
 
 	strncpy((char *)param->u.crypt.alg, alg_name, IEEE_CRYPT_ALG_NAME_LEN);
@@ -2124,6 +2125,7 @@ static int rtw_wx_set_enc_ext(struct net_device *dev,
 
 	ret =  wpa_set_encryption(dev, param, param_len);
 
+exit:
 	kfree(param);
 	return ret;
 }