ALSA/hda: intel-sdw-acpi: fetch fwnode once in sdw_intel_scan_controller()

Optimize a bit by using an intermediate 'fwnode' variable.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20241001070611.63288-3-yung-chuan.liao@linux.intel.com