Remove RawSerial protected member  functions
Remove RawSerial protected member  functions

andcor02/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,andcor02/mbed-os,mbedmicro/mbed,mbedmicro/mbed,kjbracey-arm/mbed,andcor02/mbed-os,kjbracey-arm/mbed,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os