shell: shell_uart: improve macro compatibility with previous version

The `SHELL_UART_DEFINE` macro was previously
`SHELL_UART_DEFINE(_name, _tx_ringbuf_size, _rx_ringbuf_size)`,
before it got removed in zephyrproject-rtos#63967 and then reinstated in zephyrproject-rtos#66218 as
`SHELL_UART_DEFINE(_name)`.

However its current form isn't compatible with previous Zephyr
version, and would cause compilation error when an application
migrates from to v3.6, let's modify it to accept variable
arguments for now.

Added documentation for this public API and updated the
migration guide accordingly.

Signed-off-by: Yong Cong Sin <[email protected]>

Author: ycsin

doc/releases/migration-guide-3.6.rst

@@ -242,6 +242,10 @@ Shell
   * :kconfig:option:`CONFIG_W1_SHELL`
   * :kconfig:option:`CONFIG_WDT_SHELL`
 
+* The ``SHELL_UART_DEFINE`` macro now only requires a ``_name`` argument. In the meantime, the
+  macro accepts additional arguments (ring buffer TX & RX size arguments) for compatibility with
+  previous Zephyr version, but they are ignored, and will be removed in future release.
+
 Bootloader
 ==========
 

include/zephyr/shell/shell_uart.h

@@ -81,7 +81,13 @@ struct shell_uart_polling {
 #define SHELL_UART_STRUCT struct shell_uart_int_driven
 #endif
 
-#define SHELL_UART_DEFINE(_name)                                                                   \
+/**
+ * @brief Macro for creating shell UART transport instance named @p _name
+ *
+ * @note Additional arguments are accepted (but ignored) for compatibility with
+ * previous Zephyr version, it will be removed in future release.
+ */
+#define SHELL_UART_DEFINE(_name, ...)                                                              \
 	static SHELL_UART_STRUCT _name##_shell_uart;                                               \
 	struct shell_transport _name = {                                                           \
 		.api = &shell_uart_transport_api,                                                  \