b43: Add TX statistics debugging counters

This adds a few debugging counters, that are useful for debugging the
"card does not transmit" or "connection is unstable" kind of problems.
It's also useful for tuning an RC algorithm.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43/dma.h b/drivers/net/wireless/b43/dma.h
index 9336286..ea27085 100644
--- a/drivers/net/wireless/b43/dma.h
+++ b/drivers/net/wireless/b43/dma.h
@@ -256,7 +256,13 @@
 	int max_used_slots;
 	/* Last time we injected a ring overflow. */
 	unsigned long last_injected_overflow;
-#endif				/* CONFIG_B43_DEBUG */
+	/* Statistics: Number of successfully transmitted packets */
+	u64 nr_succeed_tx_packets;
+	/* Statistics: Number of failed TX packets */
+	u64 nr_failed_tx_packets;
+	/* Statistics: Total number of TX plus all retries. */
+	u64 nr_total_packet_tries;
+#endif /* CONFIG_B43_DEBUG */
 };
 
 static inline u32 b43_dma_read(struct b43_dmaring *ring, u16 offset)