i2c: Move typedef of bitbang_i2c_interface to i2c.h

Clang 3.4 considers duplicate typedef in ppc4xx_i2c.h and
bitbang_i2c.h an error even if they are identical. Move it to a common
place to allow building with this clang version.
Reported-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NBALATON Zoltan <balaton@eik.bme.hu>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NThomas Huth <thuth@redhat.com>

hw/i2c/bitbang_i2c.h

@@ -3,8 +3,6 @@
 
 #include "hw/i2c/i2c.h"
 
-typedef struct bitbang_i2c_interface bitbang_i2c_interface;
-
 #define BITBANG_I2C_SDA 0
 #define BITBANG_I2C_SCL 1
 

include/hw/i2c/i2c.h

@@ -82,6 +82,8 @@ int i2c_recv(I2CBus *bus);
 
 DeviceState *i2c_create_slave(I2CBus *bus, const char *name, uint8_t addr);
 
+typedef struct bitbang_i2c_interface bitbang_i2c_interface;
+
 /* lm832x.c */
 void lm832x_key_event(DeviceState *dev, int key, int state);
 

include/hw/i2c/ppc4xx_i2c.h

@@ -31,9 +31,6 @@
 #include "hw/sysbus.h"
 #include "hw/i2c/i2c.h"
 
-/* from hw/i2c/bitbang_i2c.h */
-typedef struct bitbang_i2c_interface bitbang_i2c_interface;
-
 #define TYPE_PPC4xx_I2C "ppc4xx-i2c"
 #define PPC4xx_I2C(obj) OBJECT_CHECK(PPC4xxI2CState, (obj), TYPE_PPC4xx_I2C)