KVM: Remove unnecessary ->decache_regs() call

Since we aren't modifying any register, there's no need to decache
the register state.
Signed-off-by: NAvi Kivity <avi@qumranet.com>

arch/x86/kvm/x86.c

@@ -2297,7 +2297,6 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
 
 	kvm_x86_ops->cache_regs(vcpu);
 	memcpy(vcpu->arch.pio_data, &vcpu->arch.regs[VCPU_REGS_RAX], 4);
-	kvm_x86_ops->decache_regs(vcpu);
 
 	kvm_x86_ops->skip_emulated_instruction(vcpu);