add tsc_early_khz
add tsc_early_khz

Because boot stops due to tsc calibration failure when running on travis-ci.

[    0.012000][    T0] tsc: Unable to calibrate against PIT
[    0.012000][    T0] tsc: No reference (HPET/PMTIMER) available
[    0.012000][    T0] tsc: Marking TSC unstable due to could not calculate TSC khz

Signed-off-by: Nobuhiro MIKI <788ebd396d3abdc7bc39cc11ea545b3667467628@bobuhiro11.net>

bobuhiro11/gokvm,bobuhiro11/gokvm