sfc: Add workspace for GMAC bug workaround to MCDI MAC_STATS buffer

Due to a hardware bug in the SFC9000 family, the firmware must
transfer raw GMAC statistics to host memory before aggregating them
into the cooked (speed-independent) MAC statistics.  Extend the stats
buffer to support this.

The length of the buffer is explicit in the MAC_STATS command, so this
change is backward-compatible on both sides.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/sfc/mcdi_pcol.h

@@ -1090,8 +1090,10 @@
 #define MC_CMD_MAC_RX_LANES01_DISP_ERR 57
 #define MC_CMD_MAC_RX_LANES23_DISP_ERR 58
 #define MC_CMD_MAC_RX_MATCH_FAULT 59
+#define MC_CMD_GMAC_DMABUF_START 64
+#define MC_CMD_GMAC_DMABUF_END   95
 /* Insert new members here. */
-#define MC_CMD_MAC_GENERATION_END 60
+#define MC_CMD_MAC_GENERATION_END 96
 #define MC_CMD_MAC_NSTATS (MC_CMD_MAC_GENERATION_END+1)
 
 /* MC_CMD_MAC_STATS: