"debugging" is a horrible name for a global variable - thankfully it can
become static.

Also put it out of __read_mostly so that gcc no longer has to emit it
at all.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>