drivers/net/ethernet: Fix non-kernel-doc comments with kernel-doc start markers

Convert doxygen (or similar) formatted comments to kernel-doc or
unformatted comment.  Delete a few that are content-free.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/nvidia/forcedeth.c b/drivers/net/ethernet/nvidia/forcedeth.c
index c503fbe..8b7c512 100644
--- a/drivers/net/ethernet/nvidia/forcedeth.c
+++ b/drivers/net/ethernet/nvidia/forcedeth.c
@@ -3552,8 +3552,7 @@
 	return IRQ_HANDLED;
 }
 
-/**
- * All _optimized functions are used to help increase performance
+/* All _optimized functions are used to help increase performance
  * (reduce CPU and increase throughput). They use descripter version 3,
  * compiler directives, and reduce memory accesses.
  */