ARM: OMAP: Allow I2C bus driver to be compiled as a module

Fixes a linker error when OMAP I2C bus driver is compiled as a module:

   ERROR: "i2c_register_board_info" [arch/arm/plat-omap/i2c.ko] undefined!

The I2C utility functions used for board initialization should be always
built-in.
Signed-off-by: Aaro Koskinen <Aaro.Koskinen@nokia.com>
Acked-by: Jarkko Nikula  <jarkko.nikula@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/Makefile

@@ -18,7 +18,8 @@ obj-$(CONFIG_CPU_FREQ) += cpu-omap.o
 obj-$(CONFIG_OMAP_DM_TIMER) += dmtimer.o
 obj-$(CONFIG_OMAP_DEBUG_DEVICES) += debug-devices.o
 obj-$(CONFIG_OMAP_DEBUG_LEDS) += debug-leds.o
-obj-$(CONFIG_I2C_OMAP) += i2c.o
+i2c-omap-$(CONFIG_I2C_OMAP) := i2c.o
+obj-y += $(i2c-omap-m) $(i2c-omap-y)
 
 # OMAP mailbox framework
 obj-$(CONFIG_OMAP_MBOX_FWK) += mailbox.o

arch/arm/plat-omap/include/mach/common.h

@@ -35,7 +35,7 @@ extern void omap_map_common_io(void);
 extern struct sys_timer omap_timer;
 extern void omap_serial_init(void);
 extern void omap_serial_enable_clocks(int enable);
-#ifdef CONFIG_I2C_OMAP
+#if defined(CONFIG_I2C_OMAP) || defined(CONFIG_I2C_OMAP_MODULE)
 extern int omap_register_i2c_bus(int bus_id, u32 clkrate,
 				 struct i2c_board_info const *info,
 				 unsigned len);