bl updater app

This builds a second binary that will be flashed like the main firmware
and will then update the bootloader, just like the st2. It additionaly
aligns the cmsis + config with the main app, and ensures the hw is
mostly completely initalized before the main app starts, which allows
skipping the init in the main fw.

Main changes:
* bl freq 12/48Mhz -> 120Mhz
* ext 32khz disabled
* "proper" init time for xosc
* no usb init unless DFU mode is actually used
* errata 2.13.1 clock init/lock fixups
* no guessing according to f++&%! bootprog flags where the main app is

Change-Id: I1403d35497cdea41ea5bed2c94b9e729ca352772
---
A CMSIS/Include/cmsis_version.h
M atmel_start.c
M atmel_start_pins.h
M config/hpl_cmcc_config.h
M config/hpl_gclk_config.h
M config/hpl_osc32kctrl_config.h
M config/hpl_oscctrl_config.h
A config/hpl_rtc_config.h
A config/hpl_sercom_config.h
M config/peripheral_clk_config.h
M gcc/Makefile
M gcc/system_same54.c
M hpl/core/hpl_core_m4.c
M hpl/oscctrl/hpl_oscctrl.c
A hpl/sercom/hpl_sercom.c
M usb_dfu_main.c
A usb_flash_main.c
M usb_start.c
18 files changed, 6,225 insertions(+), 303 deletions(-)