x86/kvm/vmx: fix old-style function declaration

The inline keyword which is not at the beginning of the function
declaration may trigger the following build warnings, so let's fix it:

arch/x86/kvm/vmx.c:1309:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
arch/x86/kvm/vmx.c:5947:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
arch/x86/kvm/vmx.c:5985:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
arch/x86/kvm/vmx.c:6023:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]

Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>