Move the bulk of the flash.h file into flash/nor/core.h, leaving an
empty husk that will be removed in the next patch.
The NOR driver structure is an implementation detail, so move it into
its own private header file <flash/nor/driver.h> along with helper
declaration for finding them by name.
The newly moved flash TCL routines access the internals of the module
too much. Fix the layering issues by adding new core NOR flash APIs:
<flash/nor/core.h>:
- flash_driver_find_by_name() - self-descriptive
<flash/nor/imp.h>:
- flash_bank_add() - encapsulates adding banks to bank list
- flash_bank_list() - encapsulates retreiving bank list
This allows the externs in flash/nor/imp.h to be removed, and
these mechanisms may now be re-used by other flash module code.