io: stm32image: fix device_size type

Device size could be more than 4GB, we must
define size as unsigned long long.

Change-Id: I52055cf5c1c15ff18ab9e157aa9b73c8b4fb7b63
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>

include/drivers/st/io_stm32image.h

@@ -23,7 +23,7 @@ struct stm32image_part_info {
 
 struct stm32image_device_info {
 	struct stm32image_part_info part_info[STM32_PART_NUM];
-	uint32_t device_size;
+	unsigned long long device_size;
 	uint32_t lba_size;
 };