smsc95xx: Add comments to the registers definition

This chip is used by a lot of embedded devices and also by the Raspberry
Pi 1, 2 & 3 which were created to promote the study of computer
sciences. Students wanting to learn kernel / network device driver
programming through those devices can only rely on the Linux kernel
driver source to make their own.

This commit adds a lot of comments to the registers definition to expand
the register names.

Cc: Steve Glendinning <steve.glendinning@shawell.net>
Cc: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
CC: David Miller <davem@davemloft.net>
Signed-off-by: NMartin Wetterwald <martin@wetterwald.eu>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NSteve Glendinning <steve.glendinning@shawell.net>
Acked-by: NWoojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/smsc95xx.c

@@ -33,7 +33,7 @@
 #include "smsc95xx.h"
 
 #define SMSC_CHIPNAME			"smsc95xx"
-#define SMSC_DRIVER_VERSION		"1.0.5"
+#define SMSC_DRIVER_VERSION		"1.0.6"
 #define HS_USB_PKT_SIZE			(512)
 #define FS_USB_PKT_SIZE			(64)
 #define DEFAULT_HS_BURST_CAP_SIZE	(16 * 1024 + 5 * HS_USB_PKT_SIZE)
@@ -1499,7 +1499,7 @@ static int smsc95xx_enter_suspend3(struct usbnet *dev)
 	if (ret < 0)
 		return ret;
 
-	if (val & 0xFFFF) {
+	if (val & RX_FIFO_INF_USED_) {
 		netdev_info(dev->net, "rx fifo not empty in autosuspend\n");
 		return -EBUSY;
 	}