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>
diff --git a/test/utest.cpp b/test/utest.cpp
index 2297b31..279417a 100644
--- a/test/utest.cpp
+++ b/test/utest.cpp
@@ -255,7 +255,7 @@
         command(opensslCmd + pkeyFile + " -out " + pubkeyFile + ".sig " +
                 pubkeyFile);
 
-#ifdef WANT_SIGNATURE_FULL_VERIFY
+#ifdef WANT_SIGNATURE_VERIFY
         std::string fullFile = extractPath.string() + "/" + "image-full";
         command("cat " + kernelFile + ".sig " + rofsFile + ".sig " + rwfsFile +
                 ".sig " + ubootFile + ".sig " + manifestFile + ".sig " +
@@ -318,7 +318,7 @@
     EXPECT_FALSE(signature->verify());
 }
 
-#ifdef WANT_SIGNATURE_FULL_VERIFY
+#ifdef WANT_SIGNATURE_VERIFY
 /** @brief Test for failure scenario without full verification */
 TEST_F(SignatureTest, TestNoFullSignature)
 {