Bluetooth: hidp: Fix assumptions on the return value of hidp_send_message

hidp_send_message was changed to return non-zero values on success,
which some other bits did not expect. This caused spurious errors to be
propagated through the stack, breaking some drivers, such as hid-sony
for the Dualshock 4 in Bluetooth mode.

As pointed out by Dan Carpenter, hid-microsoft directly relied on that
assumption as well.

Fixes: 48d9cc9d

 ("Bluetooth: hidp: Let hidp_send_message return number of queued bytes")

Signed-off-by: Dan Elkouby <streetwalkermc@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>