x86/KVM/VMX: Separate the VMX AUTOLOAD guest/host number accounting

This allows to load a different number of MSRs depending on the context:
VMEXIT or VMENTER.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>