scd: Fix ccid-driver timeout for OpenPGPcard v2.1.

* scd/ccid-driver.c (CCID_CMD_TIMEOUT): New.
(ccid_transceive_apdu_level, ccid_transceive): Use.

It is reported that key generation causes timeout with OpenPGPcard
v2.1. Ideally, timeout value could be determined at run-time by
examining card's ATR. Compile-time fixed value is OK for internal
CCID driver.

(cherry-picked from 2.1 6510df3a7cd2b5bf44fac1e4d50ee54b8c897daa)