scd: Fix timeout handling for key generation.

* scd/ccid-driver.c (CCID_CMD_TIMEOUT): Back to original value.
(CCID_CMD_TIMEOUT_LONGER): New.
(ccid_transceive): Add kludge for key generation.

At key generation of longer key size, OpenPGP card sends back "time
extension" with BWI=100, which is unusual value in the protocol and it
actually requires host having longer timeout like 43 seconds.

• Reported-by: Szczepan Zalega <szczepan@nitrokey.com>
• Fixes-commit: 6510df3a7cd2b5bf44fac1e4d50ee54b8c897daa
• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>