fix(m5stack_tab5): don't return NULL from int bsp_get_board_version()

[vikramdattu]

bsp_get_board_version() in bsp/m5stack_tab5/src/bsp_display.c returns int, but uses BSP_ERROR_CHECK_RETURN_NULL. When CONFIG_BSP_ERROR_CHECK is disabled, that macro expands to return NULL;, so the file fails to compile with -Wint-conversion (an error with current toolchains):

bsp_display.c:138:5: error: returning 'void *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]

Any project that sets CONFIG_BSP_ERROR_CHECK=n (return-error-code style instead of abort) cannot build the Tab5 BSP.

Fix: use BSP_ERROR_CHECK(x, 0). With CONFIG_BSP_ERROR_CHECK enabled the behaviour is unchanged (ESP_ERROR_CHECK); with it disabled the function returns 0 ("version unknown") and, since board_ver only caches values > 0, the probe retries on the next call.

Hit in an app build (ESP-IDF v5.5.4, esp32p4, m5stack_tab5 1.2.0~1, CONFIG_BSP_ERROR_CHECK=n). Verified the pre-fix code reproduces the exact error under -Werror=int-conversion and the fixed code compiles clean.

---

Note

Low Risk
Localized BSP display/touch init fix and clearer error handling; behavior unchanged when error-check abort mode is enabled.

Overview
Fixes a build break when CONFIG_BSP_ERROR_CHECK=n: bsp_get_board_version() now uses BSP_ERROR_CHECK(..., 0) instead of BSP_ERROR_CHECK_RETURN_NULL, so it no longer emits return NULL from an int function (-Wint-conversion).

Display and touch setup cache the board version once per path and fail with ESP_ERR_NOT_SUPPORTED if probing did not yield version 1 or 2, instead of calling bsp_get_board_version() repeatedly and branching with separate == 2 checks.

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[espzav]

@vikramdattu Thank you for this fix. You are right.
We are waiting for this PR: #804 it can fix this issue too. But there is still discussion.