hyperv: Implement netvsc_get_channels() ethool op

This adds support for reporting the actual and maximum combined channels
count of the hv_netvsc driver via 'ethtool --show-channels'.

This required adding 'max_chn' to 'struct netvsc_device', and assigning
it 'rsscap.num_recv_que' in 'rndis_filter_device_add'. Now we can access
the combined maximum channel count via 'struct netvsc_device' in the
ethtool callback.

Signed-off-by: Andrew Schwartzmeyer <andrew@schwartzmeyer.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 384ca4f..4815843 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -634,6 +634,7 @@
 
 	struct vmbus_channel *chn_table[NR_CPUS];
 	u32 send_table[VRSS_SEND_TAB_SIZE];
+	u32 max_chn;
 	u32 num_chn;
 	atomic_t queue_sends[NR_CPUS];