scd: ccid-driver: Initial getting ATR more robustly.

* scd/ccid-driver.c (send_power_off): New.
(do_close_reader): Use send_power_off.
(ccid_get_atr): Add error recovery.

Backport from master commit of:

c51a5685554a06e00ae1e99070b44613b2f8d417

• GnuPG-bug-id: T4616
• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>