ARM: OMAP: Fix relative includes for shared i2c.h file

As discussed on linux-arm-kernel, we want to avoid
relative includes for the arch/arm/*omap* shared code:

http://www.spinics.net/lists/linux-omap/msg80520.html

To fix this for the shared i2c.h, let's re-introduce
a minimal plat/i2c.h.

Note that drivers must not use this header as it will
break build for omap2+ CONFIG_MULTIPLATFORM builds.

Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/plat-omap/i2c.c b/arch/arm/plat-omap/i2c.c
index d094273..4645dd4 100644
--- a/arch/arm/plat-omap/i2c.c
+++ b/arch/arm/plat-omap/i2c.c
@@ -31,9 +31,9 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 
-#include <mach/irqs.h>
+#include <plat/i2c.h>
 
-#include "i2c.h"
+#include <mach/irqs.h>
 
 #define OMAP_I2C_MAX_CONTROLLERS 4
 static struct omap_i2c_bus_platform_data i2c_pdata[OMAP_I2C_MAX_CONTROLLERS];