Ensure timer_read() is safe to call from interrupt handlers on ARM

[infinityis]

Context on Discord

Description

The ARM implementation of timer_read()/timer_read32() is not inherently safe to call from any context. Specifically, chSysLock()/chSysUnlock() are not safe to call from within interrupts. An example of a system that calls timer_read() from an interrupt is audio_update_state() in audio.c.

This PR replaces the chSysLock()/chSysUnlock() function calls of timer_read() with chSysGetStatusAndLockX() and chSysRestoreStatusX() instead, which are safe to call from any context.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).