r8169: Kill SafeMtu macro

After d58d46b5 (r8169: jumbo fixes.) max frame len is stored in
rtl_chip_infos[].jumbo_max for each chip and SafeMtu should be gone.
Signed-off-by: NKirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -78,7 +78,6 @@ static const int multicast_filter_limit = 32;
 
 #define MAX_READ_REQUEST_SHIFT	12
 #define TX_DMA_BURST	7	/* Maximum PCI burst, '7' is unlimited */
-#define SafeMtu		0x1c20	/* ... actually life sucks beyond ~7k */
 #define InterFrameGap	0x03	/* 3 means InterFrameGap = the shortest one */
 
 #define R8169_REGS_SIZE		256