linkmode: introduce linkmode_intersects()

Add a new helper to find intersections between Ethtool link modes,
linkmode_intersects(), similar to the other linkmode helpers.
Signed-off-by: Alexander Lobakin <alobakin@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/linkmode.h

@@ -82,6 +82,12 @@ static inline int linkmode_equal(const unsigned long *src1,
 	return bitmap_equal(src1, src2, __ETHTOOL_LINK_MODE_MASK_NBITS);
 }
 
+static inline int linkmode_intersects(const unsigned long *src1,
+				      const unsigned long *src2)
+{
+	return bitmap_intersects(src1, src2, __ETHTOOL_LINK_MODE_MASK_NBITS);
+}
+
 static inline int linkmode_subset(const unsigned long *src1,
 				  const unsigned long *src2)
 {