Bluetooth: ath3k: Fix warning: quoted string split across lines

This patch avoided the warning:
WARNING: quoted string split across lines
 #355: FILE: drivers/bluetooth/ath3k.c:355:
 +			BT_ERR("Error in firmware loading err = %d,"
 +				"len = %d, size = %d", err, len, size);

This patch fix this issue.

Signed-off-by: Maxim Zhukov <mussitantesmortem@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>