x86: move tsc definitions to were they belong

This patch wipes out the definitions of tsc_disable from processor_32.h
and move it to tsc.h, were it belongs

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>