pc110 touchpad driver: be more polite

The PC110 touchpad driver used to just assume that the hardware
exists, even though in fact the hw is extremely rare indeed, and
just requesting all the resources might stomp on some _other_
hardware.

Try to minimize the damage by realizing that the touchpad hw only
exists on old ISA-only hardware, and if we have found a PCI device,
we should not try to load the touchpad driver.

Verified to fix things for Andries Brouwer. 

drivers/input/mouse/pc110pad.c

@@ -38,6 +38,7 @@
 #include <linux/input.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
+#include <linux/pci.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -107,8 +108,22 @@ static int pc110pad_open(struct input_dev *dev)
 	return 0;
 }
 
+/*
+ * We try to avoid enabling the hardware if it's not
+ * there, but we don't know how to test. But we do know
+ * that the PC110 is not a PCI system. So if we find any
+ * PCI devices in the machine, we don't have a PC110.
+ */
 static int __init pc110pad_init(void)
 {
+	struct pci_dev *dev;
+
+	dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, NULL);
+	if (dev) {
+		pci_dev_put(dev);
+		return -ENOENT;
+	}
+
 	if (!request_region(pc110pad_io, 4, "pc110pad")) {
 		printk(KERN_ERR "pc110pad: I/O area %#x-%#x in use.\n",
 				pc110pad_io, pc110pad_io + 4);