x86/vmware: Read tsc_khz only once at boot time

x86/vmware: Read tsc_khz only once at boot time

Re-factor the vmware platform setup code to query the hypervisor for tsc
frequency only once during boot. Since the VMware hypervisor guarantees
constant TSC, calibrate_tsc now uses the saved value.

Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Acked-by: Alok N Kataria <akataria@vmware.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20161020050211.GA25304@amakhalov-virtual-machine
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>