sfc: Allow DRV_GEN events to be used outside of selftests

Formerly, efx_test_eventq_irq() assumed it was the only user of
driver generated events. Allow it to interoperate with other users.

We can create more than 16 channels, so align event codes with
a multiple of 256 not 16.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 2e6fd89..ee0ea01 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -336,7 +336,7 @@
  * @eventq: Event queue buffer
  * @eventq_read_ptr: Event queue read pointer
  * @last_eventq_read_ptr: Last event queue read pointer value.
- * @eventq_magic: Event queue magic value for driver-generated test events
+ * @magic_count: Event queue test event count
  * @irq_count: Number of IRQs since last adaptive moderation decision
  * @irq_mod_score: IRQ moderation score
  * @rx_alloc_level: Watermark based heuristic counter for pushing descriptors
@@ -367,7 +367,7 @@
 	struct efx_special_buffer eventq;
 	unsigned int eventq_read_ptr;
 	unsigned int last_eventq_read_ptr;
-	unsigned int eventq_magic;
+	unsigned int magic_count;
 
 	unsigned int irq_count;
 	unsigned int irq_mod_score;