dfu:core: Export dfu_{get|free}_buf functions

Define the dfu_get_buf() and dfu_free_buf() as global functions.
They are necessary for zero copy buffer management, when DFU backend is
used for storing data.
Signed-off-by: NLukasz Majewski <l.majewski@samsung.com>

drivers/dfu/dfu.c

@@ -67,14 +67,14 @@ int dfu_init_env_entities(char *interface, int dev)
 static unsigned char *dfu_buf;
 static unsigned long dfu_buf_size = CONFIG_SYS_DFU_DATA_BUF_SIZE;
 
-static unsigned char *dfu_free_buf(void)
+unsigned char *dfu_free_buf(void)
 {
 	free(dfu_buf);
 	dfu_buf = NULL;
 	return dfu_buf;
 }
 
-static unsigned char *dfu_get_buf(void)
+unsigned char *dfu_get_buf(void)
 {
 	char *s;
 

include/dfu.h

@@ -129,6 +129,8 @@ void dfu_trigger_reset(void);
 int dfu_get_alt(char *name);
 bool dfu_reset(void);
 int dfu_init_env_entities(char *interface, int dev);
+unsigned char *dfu_get_buf(void);
+unsigned char *dfu_free_buf(void);
 
 int dfu_read(struct dfu_entity *de, void *buf, int size, int blk_seq_num);
 int dfu_write(struct dfu_entity *de, void *buf, int size, int blk_seq_num);