[WATCHDOG] acquirewdt.c - clean before platform_device patches

Clean the current code before we convert the driver to a platform_device.
This clean consists of:
- document the includes
- make sure that the printk's use the module/driver-name
- do the exit of the module exactly the opposite of the init of the module

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>