sandbox: i2c: Move platdata structs to header files

At present the structs used by these drivers are declared in the C files
and so are not accessible to dtoc. Move them to header files, as required.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/i2c-emul-uclass.c b/drivers/i2c/i2c-emul-uclass.c
index 75d7988..9ef4651 100644
--- a/drivers/i2c/i2c-emul-uclass.c
+++ b/drivers/i2c/i2c-emul-uclass.c
@@ -7,6 +7,7 @@
 #include <dm.h>
 #include <i2c.h>
 #include <log.h>
+#include <asm/i2c.h>
 #include <dm/device-internal.h>
 #include <dm/uclass-internal.h>
 
@@ -23,18 +24,6 @@
  * uclass so avoid having strange devices on the I2C bus.
  */
 
-/**
- * struct i2c_emul_uc_plat - information about the emulator for this device
- *
- * This is used by devices in UCLASS_I2C_EMUL to record information about the
- * device being emulated. It is accessible with dev_get_uclass_plat()
- *
- * @dev: Device being emulated
- */
-struct i2c_emul_uc_plat {
-	struct udevice *dev;
-};
-
 struct udevice *i2c_emul_get_device(struct udevice *emul)
 {
 	struct i2c_emul_uc_plat *uc_plat = dev_get_uclass_plat(emul);