ARM: OMAP1: Fix compile for boards depending on old gpio expander

The long term fix is to switch boards to use drivers/gpio/pcf857x.c.
Signed-off-by: NTony Lindgren <tony@atomide.com>

include/asm-arm/arch-omap/gpioexpander.h

@@ -18,7 +18,18 @@
 
 /* Function Prototypes for GPIO Expander functions */
 
+#ifdef CONFIG_GPIOEXPANDER_OMAP
 int read_gpio_expa(u8 *, int);
 int write_gpio_expa(u8 , int);
+#else
+static inline int read_gpio_expa(u8 *val, int addr)
+{
+	return 0;
+}
+static inline int write_gpio_expa(u8 val, int addr)
+{
+	return 0;
+}
+#endif
 
 #endif /* __ASM_ARCH_OMAP_GPIOEXPANDER_H */