sfc: Maintain interrupt moderation values in ticks, not microseconds

This simplifies the implementation a lot.

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 25b7933..c8b6998 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -327,7 +327,7 @@
  * @used_flags: Channel is used by net driver
  * @enabled: Channel enabled indicator
  * @irq: IRQ number (MSI and MSI-X only)
- * @irq_moderation: IRQ moderation value (in us)
+ * @irq_moderation: IRQ moderation value (in hardware ticks)
  * @napi_dev: Net device used with NAPI
  * @napi_str: NAPI control structure
  * @reset_work: Scheduled reset work thread