Scons: Tools: Template: Added target platform and target tests

You can now test for the platform of the target in a template
file like this:
%% if target is f4
Tools: DeviceFiles: Autodetect simple template files

Drivers with only simple template files that will only
be converted to one output file that has the same name
as the input template file just withiout the '.in' now
do not need a driver xml file anymore.
STM32: Clock: Now using templates