This patch fixes the duplicated functions introduced by cpu caps
modularization.
In cpu caps modularization, function `is_vmx_disabled` was supposed
to be moved from `arch/x86/vmcs.c` to`arch/x86/cpu_caps.c`,
but the original one was not removed.
Tracked-On: #861
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>