dfu: add 'SCRIPT' entity

Define a new 'SCRIPT' type for DFU entities. The downloaded data are
treated as simple u-boot's scripts and executed with run_command_list()
function.

Flashing the 'SCRIPT' entity might result in changing the 'dfu_alt_info'
environment variable from the flashed script, so add a global variable
for tracking the potential need to reinitialize the dfu_alt_info related
structures.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

include/dfu.h

@@ -34,6 +34,7 @@ enum dfu_layout {
 	DFU_FS_EXT4,
 	DFU_RAM_ADDR,
 	DFU_SKIP,
+	DFU_SCRIPT,
 };
 
 enum dfu_op {
@@ -497,6 +498,8 @@ static inline int dfu_fill_entity_virt(struct dfu_entity *dfu, char *devstr,
 }
 #endif
 
+extern bool dfu_reinit_needed;
+
 #if CONFIG_IS_ENABLED(DFU_WRITE_ALT)
 /**
  * dfu_write_by_name() - write data to DFU medium