PPMAC - Disable limits not supported

In TurboPMAC, the limits are monitored by examining the ix24 variables. However, in PowerPMAC, ix24 represents the address of the servo-loop being used. PowerPMAC also includes protection against writing to invalid addresses.
The element `Motor[%d].pLimits` should be used instead.

This difference makes operations like `i%d24=i%d24&$FDFFFF` and `i%d24=i%d24|$20000` invalid in PowerPMAC. Moreover, these operations do not disable or enable the limits as one might expect.
The correct operation should be something like `Motor[%d].pLimits=0` for disabing, and `Motor[%d].pLimits=Gate3[%d].Chan[%d].Status.a` for enabling (preferably that address should be stored when disabling the limits).

When checking ix24, the response formats differ between TurboPMAC and PowerPMAC:
- TurboPMAC uses the `$%x` format.
- PowerPMAC uses the `%d` format.

Ultimately, these differences might lead to undesired behavior in two scenarios:
- When homing into the limits, which is necessary to disable the limit faults.
- When performing a safety check present in pmacAxis::getAxisStatus, which flags if the limits are disabled without the driver’s knowledge.