mbed fix for Infinity
=====================
Without linker script patch it doesn't place vector table in final binary.
And clock is configured to 48MHz using internal clock reference and FLL multiplication.
mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/system_MK20D5.c
Fix SystemInit: clock setup for internal clock. Inifinity has no external Xtal.
mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/cmsis_nvic.c
Fix NVIC vector address of firmware 0x1000 instead of 0x0
mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/TOOLCHAIN_GCC_ARM/MK20D5.ld
Fix memory map for Infinity bootloader
Flash starts at 0x1000
No flash config bytes sector
USBDevice/USBDevice/USBHAL_KL25Z.cpp
Fix USB clock setup, see below.
2015/01/04 Based on mbed-sdk @2f63fa7d78a26.
Kinetis USB config
==================
Clock source: Internal reference clock wth FLL
SIM_SOPT[USBSRC] = 1(MCGPLLCLK/MCGFLLCLK)
SIM_SOPT[PLLSEL] = 0(MCGFLLCLK)
Clock dividor:
SIM_CLKDIV2[USBDIV] = 0
SIM_CLKDIV2[USBFAC] = 0
Clock enable:
SIM_SCGC4[USBOTG] = 1
d0fefb76f8