[EISA] EISA registration with !CONFIG_EISA

This is a change for the EISA bus support to permit drivers to call
un/registration functions even if EISA support has not been enabled.  This is
similar to what PCI (and now TC) does and reduces the need for #ifdef clutter.
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

include/linux/eisa.h

@@ -61,10 +61,20 @@ struct eisa_driver {
 
 #define to_eisa_driver(drv) container_of(drv,struct eisa_driver, driver)
 
+/* These external functions are only available when EISA support is enabled. */
+#ifdef CONFIG_EISA
+
 extern struct bus_type eisa_bus_type;
 int eisa_driver_register (struct eisa_driver *edrv);
 void eisa_driver_unregister (struct eisa_driver *edrv);
 
+#else /* !CONFIG_EISA */
+
+static inline int eisa_driver_register (struct eisa_driver *edrv) { return 0; }
+static inline void eisa_driver_unregister (struct eisa_driver *edrv) { }
+
+#endif /* !CONFIG_EISA */
+
 /* Mimics pci.h... */
 static inline void *eisa_get_drvdata (struct eisa_device *edev)
 {