fix(decoder): fix potential mem leak in image decoder (#5077)

src/libs/libjpeg_turbo/lv_libjpeg_turbo.c

@@ -172,6 +172,7 @@ static lv_result_t decoder_open(lv_image_decoder_t * decoder, lv_image_decoder_d
                                                 decoded->data_size);
         if(cache == NULL) {
             lv_cache_unlock();
+            lv_draw_buf_destroy(decoded);
             return LV_RESULT_INVALID;
         }
 

src/libs/libpng/lv_libpng.c

@@ -162,6 +162,7 @@ static lv_result_t decoder_open(lv_image_decoder_t * decoder, lv_image_decoder_d
         lv_cache_entry_t * cache = lv_cache_add(decoded, 0, decoder->cache_data_type, decoded->data_size);
         if(cache == NULL) {
             lv_cache_unlock();
+            lv_draw_buf_destroy(decoded);
             return LV_RESULT_INVALID;
         }