r8169: Align ASPM/CLKREQ setting function with vendor driver

There's a small delay after setting ASPM in vendor drivers, r8101 and
r8168.
In addition, those drivers enable ASPM before ClkReq, also change that
to align with vendor driver.

I haven't seen anything bad becasue of this, but I think it's better to
keep in sync with vendor driver.
Signed-off-by: NKai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -4775,12 +4775,14 @@ static void rtl_pcie_state_l2l3_enable(struct rtl8169_private *tp, bool enable)
 static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
 {
 	if (enable) {
-		RTL_W8(tp, Config2, RTL_R8(tp, Config2) | ClkReqEn);
 		RTL_W8(tp, Config5, RTL_R8(tp, Config5) | ASPM_en);
+		RTL_W8(tp, Config2, RTL_R8(tp, Config2) | ClkReqEn);
 	} else {
 		RTL_W8(tp, Config2, RTL_R8(tp, Config2) & ~ClkReqEn);
 		RTL_W8(tp, Config5, RTL_R8(tp, Config5) & ~ASPM_en);
 	}
+
+	udelay(10);
 }
 
 static void rtl_hw_start_8168bb(struct rtl8169_private *tp)