[PATCH net-next] yellowfin: fix remove set but not used variable warning

[YueHaibing]

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/packetengines/yellowfin.c: In function 'yellowfin_rx':
drivers/net/ethernet/packetengines/yellowfin.c:1053:18: warning:
 variable 'yf_size' set but not used [-Wunused-but-set-variable]

This puts the variable declaration into the YF_PROTOTYPE macro.

Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 drivers/net/ethernet/packetengines/yellowfin.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/packetengines/yellowfin.c 
b/drivers/net/ethernet/packetengines/yellowfin.c
index 6f8d6584f809..edc8cc7f0d0d 100644
--- a/drivers/net/ethernet/packetengines/yellowfin.c
+++ b/drivers/net/ethernet/packetengines/yellowfin.c
@@ -1050,8 +1050,11 @@ static int yellowfin_rx(struct net_device *dev)
                struct sk_buff *rx_skb = yp->rx_skbuff[entry];
                s16 frame_status;
                u16 desc_status;
-               int data_size, yf_size;
+               int data_size;
                u8 *buf_addr;
+#ifdef YF_PROTOTYPE
+               int yf_size = sizeof(struct yellowfin_desc);
+#endif
 
                if(!desc->result_status)
                        break;
@@ -1068,8 +1071,6 @@ static int yellowfin_rx(struct net_device *dev)
                if (--boguscnt < 0)
                        break;
 
-               yf_size = sizeof(struct yellowfin_desc);
-
                if ( ! (desc_status & RX_EOP)) {
                        if (data_size != 0)
                                netdev_warn(dev, "Oversized Ethernet frame 
spanned multiple buffers, status %04x, data_size %d!\n",