KVM: selftests: Don't use a static local in vcpu_get_supported_hv_cpuid()

Don't use a static variable for the Hyper-V supported CPUID array, the
helper unconditionally reallocates the array on every invocation (and all
callers free the array immediately after use).  The array is intentionally
recreated and refilled because the set of supported CPUID features is
dependent on vCPU state, e.g. whether or not eVMCS has been enabled.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220614200707.3315957-20-seanjc@google.com