KVM: selftests: Drop a duplicate TEST_ASSERT() in vm_nr_pages_required()

Remove a duplicate TEST_ASSERT() on the number of runnable vCPUs in
vm_nr_pages_required() that snuck in during a rebase gone bad.

Reported-by: Andrew Jones <drjones@redhat.com>
Fixes: 6e1d13bf ("KVM: selftests: Move per-VM/per-vCPU nr pages calculation to __vm_create()")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220613161942.1586791-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>