Enable the following features for all boards except
nrf51 boards with SoftDevice present:
- MICROPY_VFS
- MICROPY_PY_NRF
- MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
Enabling the following features for all targets, except for nrf51
targets compiled to be used with SoftDevice:
- MICROPY_PY_ARRAY_SLICE_ASSIGN
- MICROPY_PY_SYS_STDFILES
- MICROPY_PY_UBINASCII
Splitting mpconfigport.h into multiple device specific
files in order to facilitate variations between devices.
Due to the fact that the devices might have variations in
features and also variations in flash size it makes sense
that some devices offers more functionality than others
without being limited by restricted devices.
For example more micropython features can be activated for
nrf52840 with 1MB flash, compared to nrf51 with 256KB.
