This was #define'd as 0 on all platforms, so let's get rid of it.

This change makes pci_scan_slot() slightly easier to read.

Cc: Yoshinori Sato
Cc: Tony Luck
Cc: David Howells
Cc: "David S. Miller"
Cc: Jeff Dike
Cc: Ingo Molnar
Cc: Ivan Kokshaysky
Reviewed-by: Matthew Wilcox
Acked-by: Russell King
Acked-by: Ralf Baechle
Acked-by: Kyle McMartin
Acked-by: Benjamin Herrenschmidt
Acked-by: Paul Mundt
Acked-by: Arnd Bergmann
Signed-off-by: Alex Chiang
Signed-off-by: Jesse Barnes