Support flm parameter to FlashRegion ctor.
Support flm parameter to FlashRegion ctor.

- Setting FlashRegion flm from initial attribute passed to ctor.
- FlashRegion ctor allows flm to be set in place of blocksize/sector_size.

mbedmicro/pyOCD,pyocd/pyOCD,mesheven/pyOCD,flit/pyOCD,flit/pyOCD,mbedmicro/pyOCD,mesheven/pyOCD,mbedmicro/pyOCD,mesheven/pyOCD,pyocd/pyOCD