[sync] sync from internal repo

* use nuttx libc, disable system libc
* use tlsf as default
* update lhal flash driver
* add example readme
* add flash ini for new flash tool
* add fw header for new flash tool

examples/fatfs/README.md

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+# fatfs
+
+
+## Support CHIP
+
+|      CHIP        | Remark |
+|:----------------:|:------:|
+|BL616/BL618       |        |
+|BL808             |  Only for M0 CPU      |
+
+## Compile
+
+- BL616/BL618
+
+```
+make CHIP=bl616 BOARD=bl616dk
+```
+
+- BL808
+
+```
+make CHIP=bl808 BOARD=bl808dk CPU_ID=m0
+```
+
+## Flash
+
+```
+make flash CHIP=chip_name COMX=xxx # xxx is your com name
+```

examples/fatfs/flash_prog_cfg.ini

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+[cfg]
+# 0: no erase, 1:programmed section erase, 2: chip erase
+erase = 1
+# skip mode set first para is skip addr, second para is skip len, multi-segment region with ; separated
+skip_mode = 0x0, 0x0
+# 0: not use isp mode, #1: isp mode
+boot2_isp_mode = 0
+
+[FW]
+filedir = ./build/build_out/fatfs_$(CHIPNAME).bin
+address = 0x000000