Kconfig files. Repartition some functionality. Bootloader support will need to be provided in logic under arch/z80/src/ez80 so the critical configuration selections were moved the Kconfig file there.
arch/z80/src/ez80/ez80_i2c.h: Rename arch/z80/src/ez80/ez80f91_i2c.h. It is sharable by both ez80f91 and ez80f92.
arch/z80/src/ez80/: Add logic to perform an additional level of interrupt redirection. This is necessary because the the interrupt handling is part of the loader FLASH-based logic. In order to share interrupts with the program loaded into RAM by the loader, another layer or redirection is required to get control to the interrupt handlers in the loaded program. See ez809f2_loader.asm and ez80f92_program.asm
boards/z80/ez80/z20x/scripts: Reduce size of the interrupt re-direction buffer from 1Kb to 512b.
The eZ80F92 interrupt controller is very different from the eZ80F91. The eZ80F91 has:
1. Four byte interrupt vectors
2. The vector base address register is 16-bit so the vector table can lie in RAM
Whereas the eZ80F92 has:
1. Two byte interrupt vectors
2. An 8-bit vector base address
This means that the vectors must lie in the first 16-bits of FLASH and there must be a "trampoline" to get to interrupt handlers outside of the first 64-Kb of FLASH.
