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>

diff --git a/arch/arm/plat-omap/Makefile b/arch/arm/plat-omap/Makefile
index deaff58..04a100c 100644
--- a/arch/arm/plat-omap/Makefile
+++ b/arch/arm/plat-omap/Makefile
@@ -18,7 +18,8 @@
 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