net: davinci_emac: don't teardown inactive rx channel

Tearing down an unitialized rx channel causes a pending address hole
event to be queued. When booting linux it will report this pending
as something like "Address Hole seen by USB_OTG  at address 57fff584",
since u-boot did not handled this interrupt. Prevent that by not
tearing down the rx channel, when not receiving.

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/drivers/net/davinci_emac.c b/drivers/net/davinci_emac.c
index 427ad3e..0444795 100644
--- a/drivers/net/davinci_emac.c
+++ b/drivers/net/davinci_emac.c
@@ -598,7 +598,8 @@
 	debug_emac("+ emac_close\n");
 
 	davinci_eth_ch_teardown(EMAC_CH_TX);	/* TX Channel teardown */
-	davinci_eth_ch_teardown(EMAC_CH_RX);	/* RX Channel teardown */
+	if (readl(&adap_emac->RXCONTROL) & 1)
+		davinci_eth_ch_teardown(EMAC_CH_RX); /* RX Channel teardown */
 
 	/* Reset EMAC module and disable interrupts in wrapper */
 	writel(1, &adap_emac->SOFTRESET);