fix(mtd): support for very small partition sizes of just 32B

[alexcekay]

Solved Problem

• When you have small partitions, like using 1 block of an EEPROM only in an px4_mtd_entry_t a partition of size 32 byte is used.
• The mtd systemcmd can not handle those well as it works in chunks > 32 byte, which for example causes problems with read(fd, v, sizeof(v)) == sizeof(v) when sizeof(v) > 32 (which it currently is)

Solution

• Use chunks of 32 bytes

Test coverage

• Tested with the v6s on the bench

[github-actions]

💡 Commit messages could be improved

Not blocking, but these commit messages could use some cleanup.

Commit	Message	Suggestion
1bba8348ba	Fix mtd command for very small partition sizes of just 32B	Missing conventional commit format (e.g. "feat(ekf2): add something")

See the commit message convention for details.

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