test: Remove defunct support for zmake
test: Remove defunct support for zmake

The CMakeLists in the test drivers tests maintained code to be backwards
compatible with zmake. Since we haven't supported invoking tests in
zmake for some time this is dead CMake code.

Remove it.

BRANCH=none
BUG=none
TEST=CQ

Signed-off-by: Aaron Massey <79529a820df71f45023239a3663736629646cc34@google.com>
Change-Id: I556c443f176f3a64af4c33711f2def5006434956
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3942834
Reviewed-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>

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