Change in flashrom[master]: libflashrom: Allow getting the progress_state from the flashctx

[Nico Huber (Code Review)]

Attention is currently required from: Felix Singer, Richard Hughes.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/64663 )

Change subject: libflashrom: Allow getting the progress_state from the flashctx
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Patch Set 2:

(3 comments)

Patchset:

PS2: 
Felix, thanks for the invitation. Not sure what to do, though, as I don't
understand the API.

Richard, have you tested if the current implementation works? I'm a bit
confused about when update_progress() should get called. Does it do any-
thing on a modern Intel system at all?

There are odd paths like spi_chip_read() calls into the master, which may
call spi_read_chunked() which calls update_progress(). But spi_chip_read()
calls it as well? I wonder what was the reason to do it at the chip and
programmer levels.

File include/libflashrom.h:

https://review.coreboot.org/c/flashrom/+/64663/comment/d62c7ca9_49c76e5b 
PS2, Line 85: typedef void(flashrom_progress_callback)(struct flashrom_flashctx *flashctx);
Why doesn't it get the progress passed directly?

https://review.coreboot.org/c/flashrom/+/64663/comment/f1838035_d834604b 
PS2, Line 95:  * callback.
The library user passes the progress state?