krabby: drop board.c
krabby: drop board.c

this file is unused

BUG=none
TEST=zmake configure -b krabby
BRANCH=none

Signed-off-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@google.com>
Change-Id: I0976c1bf75078fbf10fc015f9b5afcf53a8dce4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3354665
Reviewed-by: Rong Chang <3a05493f7adfb36d203f663b3bc2ba30e9d6284f@chromium.org>
Commit-Queue: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Tested-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Auto-Submit: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

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