Revert "Fail pending LOGOUT commands on session reconnect"

This seriously breaks qemu NOP timeouts and probably other things.
The reason is that the

define ISCSI_PDU_ERROR_ON_RECONNECT	0x00000016

is masking bits 0x2 and 0x4 as well.

Correctly it should read:
define ISCSI_PDU_ERROR_ON_RECONNECT	0x00000010

However, the better solution for this approach is invoke all callbacks
of PDUs which carry the ISCSI_PDU_DROP_ON_RECONNECT flag. This will
make sure that callbacks of whatever sync tasks are invoked.

This reverts commit 0407cf6aed.

include/iscsi-private.h

@@ -233,8 +233,6 @@ struct iscsi_pdu {
 #define ISCSI_PDU_DROP_ON_RECONNECT	0x00000004
 /* stop sending after this PDU has been sent */
 #define ISCSI_PDU_CORK_WHEN_SENT	0x00000008
-/* Fail the command with error on reconnect */
-#define ISCSI_PDU_ERROR_ON_RECONNECT	0x00000016
 
 	uint32_t flags;