[M] Change in flashrom[master]: dummyflasher: use new API to register shutdown function

[Alexander Goncharov (Code Review)]

Attention is currently required from: Edward O'Callaghan, Anastasia Klimchuk.

Alexander Goncharov has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/72408 )

Change subject: dummyflasher: use new API to register shutdown function
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Patch Set 3:

(2 comments)

File dummyflasher.c:

https://review.coreboot.org/c/flashrom/+/72408/comment/f356e0ba_4b39433e 
PS2, Line 79: uint8_t refs_cnt;
> Can you add a comment on this: to explain that dummyflasher can register multiple masters and they a […]

Done

https://review.coreboot.org/c/flashrom/+/72408/comment/a596b066_5a29ee0f 
PS2, Line 1416: data->refs_cnt += ((dummy_buses_supported & BUS_PROG) != BUS_NONE);
              : 	data->refs_cnt += ((dummy_buses_supported & BUS_NONSPI) != BUS_NONE);
              : 	data->refs_cnt += ((dummy_buses_supported & BUS_SPI) != BUS_NONE);
              : 
              : #if 0
              : 	data->refs_cnt += (dummy_buses_supported & BUS_PROG) ? 1 : 0;
              : 	data->refs_cnt += (dummy_buses_supported & BUS_NONSPI) ? 1 : 0;
              : 	data->refs_cnt += (dummy_buses_supported & BUS_SPI) ? 1 : 0;
              : #endif
> Another thing could be to add `&& !ret` to every condition. […]

Your last idea is exactly what we need. Thank you! Here we go :)