8139too fix for Dreamcast

Updates the 8139too driver to work with recently added
(a724605cb7a66d423a494a395f9a8ba871b8a1eb) declared coherent memory
patch for the Dreamcast.

Signed-off-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/8139too.c

@@ -168,7 +168,7 @@ static int debug = -1;
  * Warning: 64K ring has hardware issues and may lock up.
  */
 #if defined(CONFIG_SH_DREAMCAST)
-#define RX_BUF_IDX	1	/* 16K ring */
+#define RX_BUF_IDX 0	/* 8K ring */
 #else
 #define RX_BUF_IDX	2	/* 32K ring */
 #endif