Fixed a couple of compilation errors in CellularModem
Fix macros for the UBLOX_C027 target
NRF51822 - uvision exporters
[NUCLEO_F401RE] Add auto clock configuration (HSE/HSI)

Solve also the problem with the SetSysClock function not declared in
sleep.c

Conflicts:
	libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_F401RE/i2c_api.c