VMX: correct error handling in vmx_create_vmcs()

VMX: correct error handling in vmx_create_vmcs()

With the addition of vmx_add_msr() calls to construct_vmcs() there are
now cases where simply freeing the VMCS isn't enough: The MSR bitmap
page as well as one of the MSR area ones (if it's the 2nd vmx_add_msr()
which fails) may also need freeing. Switch to using vmx_destroy_vmcs()
instead.

Fixes: 3bd36952dab6 ("x86/spec-ctrl: Introduce an option to control L1D_FLUSH for HVM HAP guests")
Fixes: 53a570b28569 ("x86/spec-ctrl: Support IBPB-on-entry")
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>