socket: Don't use u8 type in uapi socket.h

Use plain 255 instead, which also avoid introducing an additional header
dependency on <linux/types.h>

Fixes: 2685924 ("txhash: Add socket option to control TX hash rethink behavior")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Link: https://lore.kernel.org/r/20220531094345.13801-1-tklauser@distanz.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: tklauser

include/uapi/linux/socket.h

@@ -31,7 +31,7 @@ struct __kernel_sockaddr_storage {
 
 #define SOCK_BUF_LOCK_MASK (SOCK_SNDBUF_LOCK | SOCK_RCVBUF_LOCK)
 
-#define SOCK_TXREHASH_DEFAULT	((u8)-1)
+#define SOCK_TXREHASH_DEFAULT	255
 #define SOCK_TXREHASH_DISABLED	0
 #define SOCK_TXREHASH_ENABLED	1