zephyr: zmake: Add warnings about deprecated flags
zephyr: zmake: Add warnings about deprecated flags

Hopefully we can get people to stop using these flags as we want to
remove them.

Let this land for a week or so then we can rip the band-aid.

BUG=b:225379781
BRANCH=none
TEST="zmake configure -b lazor" -> see warning
     "zmake configure --test test-drivers" -> see warning
     "zmake test test-drivers" -> no warning

Signed-off-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Change-Id: Ia6e33f438237a5541cacb51b2479d8554197dbac
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3536609
Reviewed-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>

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