meson: Drop legacy 'verify-signature' option

Currently there are two options for the image signature verification:
- 'verify-signature' (legacy),
- 'verify-full-signature' (current).

Drop legacy option and let the current one take its place.

Change-Id: Ia205424395179fd190e3d055159beca93cff0545
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
4 files changed