staging: pi433: remove need to recompile code to debug fifo content

Debugging content present in the FIFO register is tricky as when we read
the FIFO register that changes the content of fifo struct which reduces
number of possible ways of debugging it. Rf69 uC has the possibility of
triggering certain IRQs depending on how many items are in the FIFO
queue, so being able to know what's in there is an important way to
troubleshoot certain problems.

This patch removes the requirement of having to compile pi433 driver
with DEBUG_FIFO_ACCESS set and let that be driven by printk verbositity
level and/or dynamic debug config instead.

Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
Link: https://lore.kernel.org/r/YgCj2P59AbFFmnbA@mail.google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>