drivers: stepper: adi: tmc2209 allow instantiation of tmc2209 without msx

The current implementation of tmc2209 driver does not allow instantiation
of the driver without configuring msx pins.

Signed-off-by: Jilay Pandya <[email protected]>

Author: jilaypandya

drivers/stepper/adi_tmc/adi_tmc22xx_stepper_controller.c

@@ -172,10 +172,9 @@ static DEVICE_API(stepper, tmc22xx_stepper_api) = {
 	static const struct tmc22xx_config tmc22xx_config_##inst = {                               \
 		.common = STEP_DIR_STEPPER_DT_INST_COMMON_CONFIG_INIT(inst),                       \
 		.enable_pin = GPIO_DT_SPEC_INST_GET(inst, enable_gpios),                           \
-		.msx_pins = DT_INST_NODE_HAS_PROP(inst, msx_gpios)                                 \
-				    ? tmc22xx_stepper_msx_pins_##inst                              \
-				    : NULL,                                                        \
 		.msx_resolutions = msx_table,                                                      \
+		IF_ENABLED(DT_INST_NODE_HAS_PROP(inst, msx_gpios),				   \
+		(.msx_pins = tmc22xx_stepper_msx_pins_##inst))					   \
 	};                                                                                         \
 	static struct tmc22xx_data tmc22xx_data_##inst = {                                         \
 		.common = STEP_DIR_STEPPER_DT_INST_COMMON_DATA_INIT(inst),                         \