Changing the Imote2 CPU Frequency

See: http://tech.groups.yahoo.com/group/intel-mote2-community/message/87

Basically, you wire interface DVFS of component DVFSC (defined in tinyos-1.x/tos/platform/imote2/DVFSC.nc) and make the following call:

call DVFS.SwitchCoreFreq(416,208);
//call DVFS.SwitchCoreFreq(208,208);
//call DVFS.SwitchCoreFreq(104,104); 	// Change the CPU and bus frequencies to 104MHz.  This
	  				// also changes the voltage to the minimum amount needed
	  				// to support this speed.  
	  				// 
	  				// This was copied from: 
	  				//   contrib/imote2/test/TestSensorboard\TestSensorboardM.nc
	  				//
	  				// DVFS is defined in:
  					//   tinyos-1.x/tos/platform/imote2/DVFSC.nc