[S] Change in flashrom[main]: dummyflasher: Enable higher frequency emulation

[Sergii Dmytruk (Code Review)]

Attention is currently required from: Anastasia Klimchuk.

Sergii Dmytruk has posted comments on this change by Anastasia Klimchuk. ( https://review.coreboot.org/c/flashrom/+/84423?usp=email )

Change subject: dummyflasher: Enable higher frequency emulation
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Patch Set 2:

(4 comments)

File doc/classic_cli_manpage.rst:

https://review.coreboot.org/c/flashrom/+/84423/comment/68b97887_d8199de5?usp... :
PS2, Line 619: **Frequency**
I'd document that the range is [1Hz, 8000Mhz] and there is no delay by default.

https://review.coreboot.org/c/flashrom/+/84423/comment/354aea8a_2372dd49?usp... :
PS2, Line 620: emulated
nit:
```suggestion
    Frequency can be specified in ``Hz`` (default), ``KHz``, or ``MHz`` (not case sensitive).
```

https://review.coreboot.org/c/flashrom/+/84423/comment/04be9687_e2e02135?usp... :
PS2, Line 624: 	The delay is calculated based on the assumption that we only work with bytes and transfer at 1 bit/Hz::
```suggestion
    The delay of an SPI command is proportional to the number of bits send over SPI bus in both directions and is calculated based on the assumption that we transfer at 1 bit/Hz::
```

File dummyflasher.c:

https://review.coreboot.org/c/flashrom/+/84423/comment/3274ac80_ff09a223?usp... :
PS2, Line 1169: 		if (freq == 0) {
A similar check could be added for an upper bound.  It's quite confusing to get a zero delay all of a sudden.