test(lp_core): extend LP UART multi-device test coverage

Refactor the LP UART multi-device tests to use a single parameterised
helper pair (test_lp_uart_write_cfg / test_lp_uart_read_cfg) instead of
one-off functions per config, and extend coverage to:

- write and read tests for 5-, 6-, 7-bit and even-parity configurations
- negative tests: word-length mismatch (FRAM_ERR recovery on LP side,
  garbled receive on HP side)
- LP GPIO Matrix routing tests (SOC_LP_GPIO_MATRIX_SUPPORTED chips only):
  swaps the default TX/RX GPIO numbers so both pins go through the LP GPIO
  Matrix, covering the lp_gpio_connect_in/out_signal() branch of
  lp_uart_config_io() that was previously untested at the data-transfer
  level; the same physical cross-wiring as all other LP UART tests is reused

Add rtc_gpio_deinit() cleanup at the end of single-board LP UART tests
so configured pins are returned to HP/digital mode and do not interfere
with subsequent tests that may reuse the same GPIOs.

components/ulp/test_apps/lp_core/lp_core_basic_tests/pytest_lp_core_basic.py

@@ -1,9 +1,10 @@
-# SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2022-2026 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: CC0-1.0
 import pytest
 from pytest_embedded import Dut
 from pytest_embedded_idf import CaseTester
 from pytest_embedded_idf.utils import idf_parametrize
+from pytest_embedded_idf.utils import soc_filtered_targets
 
 
 @pytest.mark.generic
@@ -56,8 +57,28 @@ def test_lp_vad(dut: Dut) -> None:
     indirect=True,
 )
 @idf_parametrize('target', ['esp32c6'], indirect=['target'])
-def test_lp_core_multi_device(case_tester) -> None:  # type: ignore
-    case_tester.run_all_multi_dev_cases(reset=True)
+def test_lp_core_multi_device(case_tester: CaseTester) -> None:
+    # Run only non-UART multi-device cases (e.g. LP I2C); LP UART is covered
+    # by test_lp_uart_multi_device which targets all LP_CORE_SUPPORTED chips.
+    non_uart_cases = [case for case in case_tester.test_menu if 'uart' not in case.groups]
+    for case in non_uart_cases:
+        case_tester.run_multi_dev_case(case=case, reset=True)
+
+
+@pytest.mark.generic_multi_device
+@pytest.mark.parametrize('count', [2], indirect=True)
+@pytest.mark.parametrize(
+    'config',
+    [
+        'defaults',
+    ],
+    indirect=True,
+)
+@idf_parametrize('target', soc_filtered_targets('SOC_ULP_LP_UART_SUPPORTED == 1'), indirect=['target'])
+def test_lp_uart_multi_device(case_tester: CaseTester) -> None:
+    uart_cases = [case for case in case_tester.test_menu if 'uart' in case.groups and 'wakeup' not in case.groups]
+    for case in uart_cases:
+        case_tester.run_multi_dev_case(case=case, reset=True)
 
 
 @pytest.mark.generic_multi_device