[M] Change in flashrom[master]: flashrom.c: Add new erase_by_layout and walk_by_layout implementations

[Edward O'Callaghan (Code Review)]

Attention is currently required from: Simon Buhrow, Thomas Heijligen, Aarya, Anastasia Klimchuk.

Edward O'Callaghan has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/71173 )

Change subject: flashrom.c: Add new erase_by_layout and walk_by_layout implementations
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Patch Set 21: Code-Review+2

(2 comments)

File flashrom.c:

https://review.coreboot.org/c/flashrom/+/71173/comment/b626580a_b69a82f5 
PS6, Line 1701: (uint8_t*)
> The newcontents buffer may b written while aligning boundaries. […]

OK, but we should fix the `const void *` in another patch.

https://review.coreboot.org/c/flashrom/+/71173/comment/2729f8c7_5f41731c 
PS6, Line 1708: free_erase_layout(erase_layout, erasefn_count);
> `free_erase_layout(erase_layout, count_usable_erasers(flashctx));` […]

Ack