ptp: ocp: Fix NULL dereference in Adva board SMA sysfs operations

In the Linux kernel, the following vulnerability has been resolved:

ptp: ocp: Fix NULL dereference in Adva board SMA sysfs operations

On Adva boards, SMA sysfs store/get operations can call

__handle_signal_outputs() or __handle_signal_inputs() while the `irig`

and `dcf` pointers are uninitialized, leading to a NULL pointer

dereference in __handle_signal() and causing a kernel crash. Adva boards

don't use `irig` or `dcf` functionality, so add Adva-specific callbacks

`ptp_ocp_sma_adva_set_outputs()` and `ptp_ocp_sma_adva_set_inputs()` that

avoid invoking `irig` or `dcf` input/output routines.