memory.c: drop kvm.h dependency

memory.c does not use any kvm specific interfaces,
don't include kvm.h

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>