uart: fix threshold configuration loss when interrupts are disabled (IDFGH-17749)

[AbanoubSalah]

Description

Description: Fixes an asymmetric flaw in the UART driver where uart_set_rx_full_threshold and uart_set_tx_empty_threshold silently drop developer configuration updates and return ESP_OK if executed before the hardware interrupts are enabled.

Problem: Checking uart_hal_get_intr_ena_status inside setters prevents developer from setting-up initialization config. If a developer configures hardware thresholds before calling uart_driver_install or unmasking interrupts, the settings never reach HAL while the API reports ESP_OK. Meanwhile, uart_set_rx_timeout applies configurations unconditionally.

Solution: Refactored both functions to write directly to their respective HAL threshold registers unconditionally inside the critical section, aligning their architectural behavior with uart_set_rx_timeout.

Related

Fixes issue #13116

Testing

It compiles perfectly with v6.1-dev

---

Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.