[slave] Use the AL error field to inform master from failures

[Rdk-T]

At the moment the slave stack does not handle the error code.

ie:

• Fail to switch state in ESM
• Fail to load EEPROM ?

[Rdk-T]

Check if these info in ETG 1000.6 are relevant

In case of an error first the AL Status Code shall be set and then the Error Flag has to be set.
After clearing the Error Flag the AL Status Code should be cleared, too. The master shall ignore
the AL Status Code if the Error Flag is clear.
In case of a state transition from AL state Op to SafeOp with Error the output SyncManager
shall be disabled. The input SyncManager shall only be disabled in case of an error which
results in invalid inputs (input error or synchronization error).
The Output-SyncManager shall be re-enabled if the error was acknowledged and there is no
output error remaining.
The Input-SyncManager shall be re-enabled if the error was acknowledged and there is no input
error remaining.