netdev: use ARRAY_SIZE() instead of sizeof(array) / ETH_GSTRING_LEN

Using ARRAY_SIZE() on arrays of the form array[][K] makes it unnecessary
to know the value of K when checking its size.

Signed-off-by: Alejandro Martinez Ruiz <alex@flawedcode.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/pcnet32.c b/drivers/net/pcnet32.c
index 90498ff..c4b74e9 100644
--- a/drivers/net/pcnet32.c
+++ b/drivers/net/pcnet32.c
@@ -137,7 +137,7 @@
 	"Loopback test  (offline)"
 };
 
-#define PCNET32_TEST_LEN (sizeof(pcnet32_gstrings_test) / ETH_GSTRING_LEN)
+#define PCNET32_TEST_LEN	ARRAY_SIZE(pcnet32_gstrings_test)
 
 #define PCNET32_NUM_REGS 136