boards/xtensa/esp32s3: Treat return value that greater than zero as succ

board_spiflash_init() => init_storage_partition() => parse_mtd_partition()
`parse_mtd_partition()` may return value that greater than zero when succ

Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>

boards/xtensa/esp32s3/esp32s3-devkit/src/esp32s3_bringup.c

@@ -243,7 +243,7 @@ int esp32s3_bringup(void)
 
 #ifdef CONFIG_ESP32S3_SPIFLASH
   ret = board_spiflash_init();
-  if (ret)
+  if (ret < 0)
     {
       syslog(LOG_ERR, "ERROR: Failed to initialize SPI Flash\n");
     }