kukui: reduce board id mapping array size
kukui: reduce board id mapping array size

This saves 65 bytes

BUG=chromium:1034518
TEST=make
BRANCH=kukui

Change-Id: I98697af247344580b4445bbebb7f2d0229e0cd97
Signed-off-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1975001
Reviewed-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@chromium.org>
Commit-Queue: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Tested-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

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