tools: check part size is not exceeding region size
tools: check part size is not exceeding region size

If config is specified, check that part size is not
exceeding the region. Normally we now assume that
part.maxaddr() can be beyond end of rom.

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