HID: protect hid_device::bpf by CONFIG_HID_BPF

And not by CONFIG_BPF. BPF can be selected while HID_BPF does not have
to. It actually cannot be on some platforms due to Kconfig dependences.

This saves quite some bytes on those setups.

Found by https://github.com/jirislaby/clang-struct.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

include/linux/hid.h

@@ -683,9 +683,9 @@ struct hid_device {							/* device report descriptor */
 
 	unsigned int id;						/* system unique id */
 
-#ifdef CONFIG_BPF
+#ifdef CONFIG_HID_BPF
 	struct hid_bpf bpf;						/* hid-bpf data */
-#endif /* CONFIG_BPF */
+#endif /* CONFIG_HID_BPF */
 };
 
 void hiddev_free(struct kref *ref);