linkmode: Change return type of linkmode_andnot to bool

linkmode_andnot() simply returns the result of bitmap_andnot().
And the return type of bitmap_andnot() is bool.
So it makes sense for the return type of linkmode_andnot()
to also be bool.

I checked all call-sites and they either ignore the return
value or treat it as a bool.

Compile tested only.

Link: https://lore.kernel.org/netdev/68088998-4486-4930-90a4-96a32f08c490@lunn.ch/
Signed-off-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240801-linkfield-bowl-v1-1-d58f68967802@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: horms

include/linux/linkmode.h

@@ -37,8 +37,9 @@ static inline bool linkmode_empty(const unsigned long *src)
 	return bitmap_empty(src, __ETHTOOL_LINK_MODE_MASK_NBITS);
 }
 
-static inline int linkmode_andnot(unsigned long *dst, const unsigned long *src1,
-				  const unsigned long *src2)
+static inline bool linkmode_andnot(unsigned long *dst,
+				   const unsigned long *src1,
+				   const unsigned long *src2)
 {
 	return bitmap_andnot(dst, src1, src2,  __ETHTOOL_LINK_MODE_MASK_NBITS);
 }