s390x/config: Do not include full pci.mak

pci.mak includes a lot of devices - and most of them do not make
sense on s390x, like USB controllers or audio cards. These devices
also show up when running "qemu-system-s390x -device help" and thus
could raise the hope for the users that they could use these kind
of devices with qemu-system-s390x. To avoid this confusion, we
should not include pci.mak and rather include the bare minimum
manually instead.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Message-Id: <1426169954-6062-1-git-send-email-thuth@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>