[PATCH] PCI: Add a "enable" sysfs attribute to the pci devices to allow userspace...

This patch adds an "enable" sysfs attribute to each PCI device. When read it
shows the "enabled-ness" of the device, but you can write a "0" into it to
disable a device, and a "1" to enable it.

This later is needed for X and other cases where userspace wants to enable
the BARs on a device (typical example: to run the video bios on a secundary
head). Right now X does all this "by hand" via bitbanging, that's just evil.
This allows X to no longer do that but to just let the kernel do this.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
CC: Peter Jones <pjones@redhat.com>
Acked-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>