zephyr: remove unused compiler definitions
zephyr: remove unused compiler definitions

Remove the CHIP_FAMILY_ and CHIP_VARIANT_ preprocessor definitions that
are not used.

BUG=none
BRANCH=none
TEST=zmake testall

Signed-off-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Change-Id: Ied1d49495109ea99029196d4ad65462381c2581b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2777124
Commit-Queue: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Reviewed-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>

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