r8169: prepare rtl_hw_aspm_clkreq_enable for usage in atomic context

Bail out if the function is used with chip versions that don't support
ASPM configuration. In addition remove the delay, it tuned out that
it's not needed, also vendor driver r8125 doesn't have it.
Suggested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169_main.c

@@ -2741,6 +2741,9 @@ static void rtl_disable_exit_l1(struct rtl8169_private *tp)
 
 static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
 {
+	if (tp->mac_version < RTL_GIGA_MAC_VER_32)
+		return;
+
 	/* Don't enable ASPM in the chip if OS can't control ASPM */
 	if (enable && tp->aspm_manageable) {
 		rtl_mod_config5(tp, 0, ASPM_en);
@@ -2770,8 +2773,6 @@ static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
 		rtl_mod_config2(tp, ClkReqEn, 0);
 		rtl_mod_config5(tp, ASPM_en, 0);
 	}
-
-	udelay(10);
 }
 
 static void rtl_set_fifo_size(struct rtl8169_private *tp, u16 rx_stat,