Bluetooth: btmrvl_sdio: Refactor irq wakeup

Use device_init_wakeup to allow the Bluetooth dev to wake the system
from suspend. Currently, the device can wake the system but no
power/wakeup entry is created in sysfs to allow userspace to disable
wakeup.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>