vmm vmx: Add VMX_CTR* wrapper macros.

These macros are similar to VCPU_CTR* but accept a single vmx_vcpu
pointer as the first argument instead of separate vm and vcpuid.

Reviewed by: corvink, markj
Differential Revision: https://reviews.freebsd.org/D37154

(cherry picked from commit 57e0119ef3a95d7faa11c44b1acbb8193aadfb35)