Kinetis chip Adding K66 and inlcuding MCG versioning

  This includes arch/arm/include/kinetis/kinetis_mcg.h
  to bring in the MCG versioning and defines the KINETIS_K66
  family for the added SoCs:

   --------------- ------- --- ------- ------- ------ ------ ------ -----
   PART NUMBER     CPU     PIN PACKAGE  TOTAL  PROGRAM EEPROM SRAM  GPIO
                   FREQ    CNT          FLASH  FLASH
   --------------- ------- --- ------- ------- ------ ------ ------ -----
   MK66FN2M0VMD18  180 MHz 144 MAPBGA   2   MB    —    — KB  260 KB 100
   MK66FX1M0VMD18  180 MHz 144 MAPBGA  1.25 MB  1 MB   4 KB  256 KB 100
   MK66FN2M0VLQ18  180 MHz 144 LQFP     2   MB    —    — KB  260 KB 100
   MK66FX1M0VLQ18  180 MHz 144 LQFP    1.25 MB  1 MB   4 KB  256 KB 100