arcnet: com20020: replace magic numbers with readable macros

This patch replaces all magic numbers in the driver with
proper named macros. For the case of XTOcfg and STARTIOcmd
it introduces the new macros.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>

drivers/net/arcnet/com20020.h

@@ -86,6 +86,7 @@ struct com20020_dev {
 /* in the CONFIG register */
 #define RESETcfg	0x80	/* put card in reset state */
 #define TXENcfg		0x20	/* enable TX */
+#define XTOcfg(x)	((x) << 3)	/* extended timeout */
 
 /* in SETUP register */
 #define PROMISCset	0x10	/* enable RCV_ALL */