I ran into this as well on an ASA5516 and found that I needed to use the "SNMP Cisco System Health Sensor". I had originally found that I could change the OID in the CPU sensor to 220.127.116.11.18.104.22.168.22.214.171.124.1.8.1, but later learned that was only monitoring 1 of 4 processors. Please see the response Paessler support gave me below. Using the "SNMP Cisco System Health Sensor" worked for me.
Your ASA appears to provide the OID's used by the "SNMP Cisco System Health Sensor", have you tried deploying this sensor?
The sensor will try with 126.96.36.199.188.8.131.52.184.108.40.206.1.4, if not found it will use 220.127.116.11.18.104.22.168.22.214.171.124.1.7 which is available according to your walk file.
You should also be able to manually create the sensors for the following OID's:
126.96.36.199.188.8.131.52.184.108.40.206.1.8.1 = "3" [ASN_UNSIGNED]
220.127.116.11.18.104.22.168.22.214.171.124.1.8.2 = "3" [ASN_UNSIGNED]
126.96.36.199.188.8.131.52.184.108.40.206.1.8.3 = "3" [ASN_UNSIGNED]
220.127.116.11.18.104.22.168.22.214.171.124.1.8.4 = "3" [ASN_UNSIGNED]
The 126.96.36.199.188.8.131.52.184.108.40.206.1.8 OID stands for cpmCPUTotal5minRev.
Please mind that you need 4 sensor's because the device reports 4 distinct CPUs. The "SNMP Custom Advanced Sensor" should be able to measure all OID's in a single sensor, but using the "SNMP Cisco System Health Sensor" would be the appropriate solution.