flashpage currently requires pagewise implementation with an optional
extension for per block writes (flashpage_raw). Most implementations
with flashpage_raw implement the pagewise access via the flashpage_raw
functions. This commit makes the flashpage raw the main access method
and adds an extension feature for the pagewise access.
The functions and defines are renamed to reflect this. The API is also
extended with a dedicated function for erasing a sector.
- Since flash access is shared with CPU2 we resize ROM_LEN
according to CPU2 secure flash memmory area.
- Add assert to prevent unauthorized reads from CPU2 secure
flash area