[NUCLEO_L152RE] Add automatic HSE/HSI clock configuration.

Update also SPI prescaler and use mbed_sdk_init() function.
[NUCLEO_F103RB] Add automatic HSE/HSI clock configuration

And:
- restart PLL in deepsleep function
- add more pins for SPI (the mbed pinout will be updated soon)
Merge branch 'master' of https://github.com/mbedmicro/mbed
[NUCLEO_F302R8] Change PWM_OUT signal assignation

The PWM output is not available on PB_3 because the TIMER2 is used by
the us_ticker.
Merge pull request #235 from bcostm/master

[NUCLEO_L152RE/F103RB] Add automatic HSE/HSI clock configuration.