rv: Fully convert enabled_monitors to use list_head as iterator

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: rv: Fully convert enabled_monitors to use list_head as iterator The callbacks in enabled_monitors_seq_ops are inconsistent. Some treat the iterator as struct rv_monitor *, while others treat the iterator as struct list_head *. This causes a wrong type cast and crashes the system as reported by Nathan. Convert everything to use struct list_head * as iterator. This also makes enabled_monitors consistent with available_monitors.

References

• https://git.kernel.org/stable/c/8948a0338d33c4a7ef1e0c439a3ad1d5fe9355ae
• https://git.kernel.org/stable/c/103541e6a5854b08a25e4caa61e990af1009a52e