Change references to flashrom-stable

Adapt all mentions of the mailing list and also the version print.

Change-Id: Ib4a3271422ee6cf4d0efb8c3fa858b66a22c0a33
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/70922
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
23 files changed