style(llcc68): apply shared clang-format

Add a .clang-format file to the LLCC68 submodule so it can be formatted consistently when edited or checked out independently from the parent repository.

Reformat the tracked C and C++ driver sources with the shared style configuration.

include/llcc68_raw.h

@@ -15,9 +15,9 @@ extern "C" {
 typedef void (*llcc68_user_dio1_handler_t)(const struct device *dev, void *user_data);
 
 enum llcc68_rf_switch_mode {
-	LLCC68_RF_SWITCH_NONE = 0,
+	LLCC68_RF_SWITCH_NONE               = 0,
 	LLCC68_RF_SWITCH_GPIO_COMPLEMENTARY = 1,
-	LLCC68_RF_SWITCH_DIO2_SINGLE = 2,
+	LLCC68_RF_SWITCH_DIO2_SINGLE        = 2,
 };
 
 struct llcc68_config {