Add KL25Z upload method support, upconvert ARDUINO form factor

[multiplemonomials]

Summary of changes

Someone at work was giving away his old FRDM-KL25Z board, and I snapped it up! Now we can test Mbed on this target.

This board is one of the oldest and smallest targets that Mbed supports, and since this Freescale chip relies heavily on IDE generated code (Processor Expert) the entire Mbed HAL for it was handwritten by Mbed!

This PR does some basic tasks to make life on this chip easier, including adding an upload method and fixing the old form factor (ARDUINO) which was causing a number of compiler warnings.

Impact of changes

• KL25Z target builds without warnings
• KL25Z target now has an upload method config file

Migration actions required

Documentation

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Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[X] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[X] Tests / results supplied as part of this PR

I uploaded a Greentea run to the Mbed generated site!