baseboard/dedede: Enable LTO
baseboard/dedede: Enable LTO

Before LTO (corori2):

RO: 224 bytes in flash and 24704 bytes in RAM still available
RW: 404 bytes in flash and 24704 bytes in RAM still available

After LTO (corori2):

RO: 8160 bytes in flash and 24896 bytes in RAM still available
RW: 8296 bytes in flash and 24896 bytes in RAM still available

BRANCH=none
BUG=b:238433667
TEST=make buildall

Signed-off-by: Tom Hughes <fc5c12f30a5ed2baa0581f44ee14ad1eb7b20d83@chromium.org>
Change-Id: I8a5e8118eefcb7b117ebefea5f15105bf4068fd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3761357
Reviewed-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

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