USB EHCI: reset root hub

Some of multi-function USB controllers (e.g. ISP1562) allow root hub
resetting only via EHCI registers. So, this patch adds the
corresponding kind of reset to OHCI's hc_reset() if the newly
introduced CONFIG_PCI_EHCI_DEVNO option is set (e.g. for Socrates
board).

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
Acked-by: Markus Klotzbuecher <mk@denx.de>
diff --git a/drivers/usb/usb_ohci.h b/drivers/usb/usb_ohci.h
index 380cb4c..7a04bf5 100644
--- a/drivers/usb/usb_ohci.h
+++ b/drivers/usb/usb_ohci.h
@@ -195,6 +195,9 @@
 	} roothub;
 } __attribute((aligned(32)));
 
+/* Some EHCI controls */
+#define EHCI_USBCMD_OFF		0x20
+#define EHCI_USBCMD_HCRESET	(1 << 1)
 
 /* OHCI CONTROL AND STATUS REGISTER MASKS */