x86: Move tsc_init to late_time_init

We do not need the TSC before late_time_init. Move the tsc_init to the
late time init code so we can also utilize HPET for calibration (which
we claimed to do but never did except in some older kernel
version). This also helps Moorestown to calibrate the TSC with the
AHBT timer which needs to be initialized in late_time_init like HPET.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>