KVM: Add missing MODULE_DESCRIPTION()

Add a module description for kvm.ko to fix a 'make W=1' warning:

  WARNING: modpost: missing MODULE_DESCRIPTION() in arch/x86/kvm/kvm.o

Opportunistically update kvm_main.c's comically stale file comment to
match the module description.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://lore.kernel.org/r/20240622-md-kvm-v2-1-29a60f7c48b1@quicinc.com
[sean: split x86 changes to a separate commit, remove stale VT-x comment]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: jeff-t-johnson

virt/kvm/kvm_main.c

@@ -1,9 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Kernel-based Virtual Machine driver for Linux
- *
- * This module enables machines with Intel VT-x extensions to run virtual
- * machines without emulation or binary translation.
+ * Kernel-based Virtual Machine (KVM) Hypervisor
  *
  * Copyright (C) 2006 Qumranet, Inc.
  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
@@ -74,6 +71,7 @@
 #define ITOA_MAX_LEN 12
 
 MODULE_AUTHOR("Qumranet");
+MODULE_DESCRIPTION("Kernel-based Virtual Machine (KVM) Hypervisor");
 MODULE_LICENSE("GPL");
 
 /* Architectures should define their poll value according to the halt latency */