nVMX: Expect #GP on VMXON with "generic" invalid CR0/CR4 bits

Expect #GP, not #UD, when executing with "generic" invalid CR0/CR4 bits,
i.e. with invalid bits other than CR0.PE or CR4.VMXE.  The PE and VMXE
checks are special pre-conditions to VM-Exit and thus #UD, all other
CR0/CR4 checks are performed if and only if the CPU isn't already in
VMX mode and so #GP.

Reported-by: Eric Li <ercli@ucdavis.edu>
Fixes: f7b730bc ("nVMX: Add subtest to verify VMXON succeeds/#UDs on good/bad CR0/CR4")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221005235422.64897-1-seanjc@google.com