Added SPI transaction settings for STM32

[jacky4566]

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Pull request details

• Please check if the PR fulfills these requirements

• The commit message/s explain/s all the changes clearly
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Bug fix
• Added feature
• Documentation update
• Other - Please explain here:

• What is the current behavior? (You can also link to an open issue here)

Boards with STM32 chips using SPI1 or SPI2 will default to base clock speed

• What is the new behavior? (if this is a feature change)

Boards with STM32 chips using SPI1 or SPI2 will now respect flash.setClock()

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

Should not break anything.

• Other information:

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