This adds the ability to rescan the pci bus for newly inserted,
reprogrammed or previously disabled pci devices.
To initiate a rescan you need to write '1' to any of the
/sys/bus/pci/slots/*/power control files. No known pci devices
will be touched.
Additionally this fixes a bug, when someone tries to disable
a device with subfunctions. The subfunctions will be disabled first now.

Short demo:
 # modprobe fakephp
 # ls /sys/bus/pci/slots | grep "0000:04"
0000:04:02.0
0000:04:02.1
0000:04:02.2
0000:04:03.0
0000:04:03.1
 # echo -n 0 > /sys/bus/pci/slots/0000\:04\:02.0/power
 # ls /sys/bus/pci/slots | grep "0000:04"
0000:04:03.0
0000:04:03.1
 # echo -n 1 > /sys/bus/pci/slots/0000\:03\:01.0/power
 # ls /sys/bus/pci/slots | grep "0000:04"
0000:04:02.0
0000:04:02.1
0000:04:02.2
0000:04:03.0
0000:04:03.1
 # lspci | grep "0000:04"
0000:04:02.0 Multimedia audio controller: Creative Labs SB Audigy (rev 03)
0000:04:02.1 Input device controller: Creative Labs SB Audigy MIDI/Gameport (rev 03)
0000:04:02.2 FireWire (IEEE 1394): Creative Labs SB Audigy FireWire Port
0000:04:03.0 SCSI storage controller: Adaptec AHA-3960D / AIC-7899A U160/m (rev 01)
0000:04:03.1 SCSI storage controller: Adaptec AHA-3960D / AIC-7899A U160/m (rev 01)
Signed-off-by: Jan Dittmer <jdittmer@ppp0.net>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>