NUCLEO_F401RE: Change system clock to 84 MHz using HSI + PLL

Update also HSE_VALUE and SPI prescaler value.
Merge branch 'master' of https://github.com/mbedmicro/mbed

Conflicts:
	libraries/mbed/targets/cmsis/TARGET_STM/TARGET_NUCLEO_F401RE/stm32f4xx_hal_conf.h
	libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_F401RE/spi_api.c
Merge branch 'master' of https://github.com/mbedmicro/mbed
[NUCLEO_F302R8] Add cmsis files (first part)
[NUCLEO_F302R8] Add cmsis files (2nd part)
[NUCLEO_F302R8] Add cmsis files (last part)
[NUCLEO_F302R8] Add hal files
[NUCLEO_F401RE] Restart PLL after deepsleep
[NUCLEO_F401RE] Add more SERIAL and PWM pins
[NUCLEO_F401RE] Add more ANALOG_IN, I2C and SPI pins
[NUCLEO_F401RE] Add INTERRUPT_IN to all pins
[NUCLEO_F401RE] Put back SERIAL_TX and SERIAL_RX pins

Even if it is a duplication of USB_TX/RX pins, it is better to have them
available.
[NUCLEO_F401RE] Typo corrections
Merge pull request #215 from bcostm/master

[NUCLEO_F302R8] Add cmsis and hal files + change F401RE clock to 84MHz