boot: Rename fit_image_get_data()

This function can only be used with FITs that use embedded data. Rename
it so this is clear.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/image.h b/include/image.h
index ab96510..e54e219 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1160,8 +1160,8 @@
 int fit_image_get_comp(const void *fit, int noffset, uint8_t *comp);
 int fit_image_get_load(const void *fit, int noffset, ulong *load);
 int fit_image_get_entry(const void *fit, int noffset, ulong *entry);
-int fit_image_get_data(const void *fit, int noffset,
-				const void **data, size_t *size);
+int fit_image_get_emb_data(const void *fit, int noffset, const void **data,
+			   size_t *size);
 int fit_image_get_data_offset(const void *fit, int noffset, int *data_offset);
 int fit_image_get_data_position(const void *fit, int noffset,
 				int *data_position);