[JianyuWang0623]

Summary

Fix three bugs in the sparse chunk walk of fastboot_flash_program():

• DONT_CARE now advances the output offset.
• CRC32 now skips its 4-byte payload.
• FILL now reads its pattern with le32toh(); the sparse format is little-endian.

Impact

Sparse images flashed via fastbootd are no longer corrupted. No API or build change.

Testing

sim:nsh + CONFIG_SYSTEM_FASTBOOTD=y builds clean. Flashed on
lckfb-szpi-esp32s3:fastboot with fastboot flash ram1 sparse_test.img, then
read back with hexdump.

Test image (blk_sz 4096): RAW, DONT_CARE, FILL 0x11223344, CRC32, RAW.
Expected: RAW1 at 0, hole at 4096, FILL at 8192, RAW2 at 12288.

Before:

nsh> hexdump /dev/ram1 count=16
0000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
nsh> hexdump /dev/ram1 skip=4096 count=16
0000: 11 22 33 44 11 22 33 44 11 22 33 44 11 22 33 44
nsh> hexdump /dev/ram1 skip=8192 count=16
0000: de ed df df f8 12 18 50 df f1 17 a7 4d f3 7f fd
nsh> hexdump /dev/ram1 skip=12288 count=16
0000: 48 28 06 d4 a9 67 df e7 05 8d 90 02 9c 51 17 42

After:

nsh> hexdump /dev/ram1 count=16
0000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
nsh> hexdump /dev/ram1 skip=4096 count=16
0000: fe fe 67 21 51 1c b9 6a 81 31 76 93 7c 8b f7 ff
nsh> hexdump /dev/ram1 skip=8192 count=16
0000: 44 33 22 11 44 33 22 11 44 33 22 11 44 33 22 11
nsh> hexdump /dev/ram1 skip=12288 count=16
0000: 0d 14 1b 22 29 30 37 3e 45 4c 53 5a 61 68 6f 76