[POWERPC] Add a field for each specific bus to struct pci_controller

Struct pci_controller doesn't prepare for the dependent data of each
specific bus. This patch adds private member to struct pci_controller.

Signed-off-by: Kou Ishizaki <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

include/asm-powerpc/pci-bridge.h

···
 	unsigned long buid;
 	unsigned long dma_window_base_cur;
 	unsigned long dma_window_size;
+
+	void *private_data;
 };
 
 /*