Printk Cleanups Ready For Linux 6.6 - Stepping Towards Threaded/Atomic Console Printing

A set of printk clean-ups were sent in today for the Linux 6.6 merge window. These clean-ups are important as they are a stepping stone towards the threaded / atomic console printing and in turn that is the last major blocker before the real-time (PREEMPT_RT) support can finally be upstreamed in the kernel...