Add error handling.
Add error handling.

* src/slots.c (slots_update_slot): Ignore GPG_ERR_ENODEV too.

--
In GnuPG 2.1, scdamon can return GPG_ERR_ENODEV.

Signed-off-by: NIIBE Yutaka <34feb69f206f6fec69fb4bd79c126fcbde2c8e6a@fsij.org>

gpg/scute,gpg/scute,gpg/scute