Kconfig: fix typo
Kconfig: fix typo

SHA25 -> SHA256

BUG=none
TEST=zmake build krabby, no warning message about unsatisfied
     dependencies
BRANCH=none

Signed-off-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@google.com>
Change-Id: I954f29f291d3a9a7ea5aeb5a7bdcdbdc6226d229
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4045297
Auto-Submit: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Tested-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Commit-Queue: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>
Reviewed-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@google.com>
Code-Coverage: Zoss <345cf107e82c70959d46f59d98bddc98ce458aff@prod.google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec