pic32cz fixes: better reset clock and uart restoration

[rizlik]

No description provided.

[Copilot]

Pull request overview

Improves PIC32CZ boot handoff behavior by deinitializing the debug UART before clock reset, adding a small PLL regulator settle delay and restoration logic, and adjusting the default wolfHSM PIC32CZ port path configuration.

Changes:

• Add uart_deinit() for PIC32CZ SERCOM1 UART and call it before pic32_clock_reset() when preparing to boot.
• Track whether the SUPC PLL regulator was already enabled at reset, add a settle delay after enabling it, and restore the regulator state before boot.
• Change WOLFHSM_MICROCHIP_PIC32CZ from a required setting to a defaulted value in arch.mk.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
hal/uart/uart_drv_pic32cz.c	Adds UART deinitialization to drain TX, disable/reset SERCOM, and release pin muxing before clock reset.
hal/pic32cz.c	Tracks PLL regulator initial state, adds a settle delay after enabling it, deinitializes UART before clock reset, and restores PLL regulator state.
arch.mk	Defaults the wolfHSM PIC32CZ port path variable instead of hard-erroring when unset.

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