mac802154: fix byteorder issues

Running make C=2 occurs these warnings:

cast from restricted __be64
incorrect type in argument 1 (different base types)
expected unsigned long long[unsigned] [usertype] val
got restricted __be64 [usertype]<noident>
cast from restricted __be64
cast to restricted __le64

This patch fix these warnings by forcing to __le64 type and using swabp64
instead swab64.
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Reported-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/mac802154.h

@@ -215,12 +215,12 @@ struct ieee802154_ops {
 };
 
 /**
- * ieee802154_netdev_to_extended_addr - convert __be64 u8 pointer to __le64
+ * ieee802154_netdev_to_extended_addr - convert big endian 64 byte void pointer to __le64
  * @dev_addr: big endian address pointer like netdevice dev_addr attribute
  */
-static inline __le64 ieee802154_netdev_to_extended_addr(const u8 *dev_addr)
+static inline __le64 ieee802154_netdev_to_extended_addr(const void *dev_addr)
 {
-	return (__le64)swab64(*((__be64 *)dev_addr));
+	return (__force __le64)swab64p(dev_addr);
 }
 
 /* Basic interface to register ieee802154 hwice */