stmmac: add header inclusion protection

This patch adds "#ifndef __<header>_H" for protecting header from double
inclusion.

Signed-off-by: Rayagond Kokatanur <rayagond@vayavyalabs.com>
Hacked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index e2d0832..719be39 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -22,6 +22,9 @@
   Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
 *******************************************************************************/
 
+#ifndef __COMMON_H__
+#define __COMMON_H__
+
 #include <linux/etherdevice.h>
 #include <linux/netdevice.h>
 #include <linux/phy.h>
@@ -366,3 +369,5 @@
 
 extern void dwmac_dma_flush_tx_fifo(void __iomem *ioaddr);
 extern const struct stmmac_ring_mode_ops ring_mode_ops;
+
+#endif /* __COMMON_H__ */