usb: dfu: f_dfu: Provide infrastructure to adjust DFU's Poll Timeout value

It is necessary to deter the host from sending subsequent DFU_GETSTATUS
request in the case of e.g. writing the buffer to medium.

Here the timeout is increased when we fill up the whole buffer. This delay
allows eMMC memory to perform its internal operations.
Otherwise we end up with HOST's error regarding GET_STATUS receive timeout.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>

include/dfu.h

@@ -77,6 +77,9 @@ static inline unsigned int get_mmc_blk_size(int dev)
 #ifndef CONFIG_SYS_DFU_MAX_FILE_SIZE
 #define CONFIG_SYS_DFU_MAX_FILE_SIZE CONFIG_SYS_DFU_DATA_BUF_SIZE
 #endif
+#ifndef DFU_DEFAULT_POLL_TIMEOUT
+#define DFU_DEFAULT_POLL_TIMEOUT 0
+#endif
 
 struct dfu_entity {
 	char			name[DFU_NAME_SIZE];