KVM: x86: Add missing MODULE_DESCRIPTION() macros

KVM: x86: Add missing MODULE_DESCRIPTION() macros

Add module descriptions for the vendor modules to fix allmodconfig
'make W=1' warnings:

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

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 kvm.ko change to separate commit]
Signed-off-by: Sean Christopherson <seanjc@google.com>