pci-host: update uncorresponding description

Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

hw/pci-host/pam.c

 /*
- * QEMU i440FX/PIIX3 PCI Bridge Emulation
+ * QEMU Smram/pam logic implementation
  *
  * Copyright (c) 2006 Fabrice Bellard
  * Copyright (c) 2011 Isaku Yamahata <yamahata at valinux co jp>