[WATCHDOG] Fix pcwd_init_module crash

Fix for the problem detected by Ingo Molnar:
enabling CONFIG_PCWATCHDOG=y crashes bzImage bootup.

The reason for this can be found in drivers/makefile
We first do:
obj-y                           += char/
and later we do:
obj-y                           += base/ block/ misc/ mfd/ net/ media/

So if we put a platform or isa or usb bus driver in char/watchdog
(which is called from the Makefile in drivers/char/Makefile)
then we didn't have the different device drivers initialized yet
(they are in drivers/base and drivers/usb and ...)

This fix makes sure that we compile the watchdog drivers after
drivers/base, drivers/misc, drivers/pci and drivers/usb.
We also do the compile after hwmon because in the future the
watchdog temperature support will use the hwmon system.

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