scd: Internal CCID: Handle LIBUSB_ERROR_TIMEOUT at ccid_get_atr.

* scd/ccid-driver.c (ccid_slot_status): Handle LIBUSB_ERROR_TIMEOUT.

With SPR532, at the first connection, it fails by
LIBUSB_ERROR_TIMEOUT, but no retry.

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