fix(img): fix getting the image type on big endian systems (#4215)

src/draw/lv_draw_img.c

@@ -198,11 +198,19 @@ lv_img_src_t lv_img_src_get_type(const void * src)
     if(src == NULL) return img_src_type;
     const uint8_t * u8_p = src;
 
-    /*The first byte shows the type of the image source*/
+    /*The first or fourth byte depending on platform endianess shows the type of the image source*/
+#if LV_BIG_ENDIAN_SYSTEM
+    if(u8_p[3] >= 0x20 && u8_p[3] <= 0x7F) {
+#else
     if(u8_p[0] >= 0x20 && u8_p[0] <= 0x7F) {
+#endif
         img_src_type = LV_IMG_SRC_FILE; /*If it's an ASCII character then it's file name*/
     }
+#if LV_BIG_ENDIAN_SYSTEM
+    else if(u8_p[3] >= 0x80) {
+#else
     else if(u8_p[0] >= 0x80) {
+#endif
         img_src_type = LV_IMG_SRC_SYMBOL; /*Symbols begins after 0x7F*/
     }
     else {