scd: Fix the use case of verify_chv2 by CHECKPIN.

* scd/app-openpgp.c (verify_chv2): Call verify_a_chv with chvno=1
when needed.

Confusingly, verify_chv2 has two different purposes; One for
verifying with CHV2 (in addition to CHV1), and the call by
CHECKPIN. For the latter, we should check CHV1.

• Fixes-commit: af189be481df02a77e088aa0a60a1fc02dfa12bf
• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>