PCI subsystem: Refactor PCI bridge register control

Change-Id: I1766c92abe7a74326c49df74ba38930a502fcb5b
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/8536
Tested-by: build bot (Jenkins)
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/include/device/device.h

@@ -81,6 +81,7 @@ struct bus {
 	ROMSTAGE_CONST struct device * 	children;	/* devices behind this bridge */
 	ROMSTAGE_CONST struct bus	*next;		/* The next bridge on this device */
 	unsigned	bridge_ctrl;	/* Bridge control register */
+	uint16_t	bridge_cmd;		/* Bridge command register */
 	unsigned char	link_num;	/* The index of this link */
 	uint16_t	secondary; 	/* secondary bus number */
 	uint16_t	subordinate;	/* max subordinate bus number */