net/macb: fix sparse warning

this patch fixes following sparse warning:

macb.c:2038:26: warning: symbol 'gem_ethtool_ops' was not declared. Should it be static?

Alongside drops exporting of gem_ethtool_ops as there is no need.
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/cadence/macb.c

@@ -2035,7 +2035,7 @@ const struct ethtool_ops macb_ethtool_ops = {
 };
 EXPORT_SYMBOL_GPL(macb_ethtool_ops);
 
-const struct ethtool_ops gem_ethtool_ops = {
+static const struct ethtool_ops gem_ethtool_ops = {
 	.get_settings		= macb_get_settings,
 	.set_settings		= macb_set_settings,
 	.get_regs_len		= macb_get_regs_len,
@@ -2046,7 +2046,6 @@ const struct ethtool_ops gem_ethtool_ops = {
 	.get_strings		= gem_get_ethtool_strings,
 	.get_sset_count		= gem_get_sset_count,
 };
-EXPORT_SYMBOL_GPL(gem_ethtool_ops);
 
 int macb_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 {