ALSA: intel_hdmi: Use strlcpy() instead of strncpy()

hdmi_lpe_audio_probe() copies the pcm name string via strncpy(), but
as a gcc8 warning suggests, it misses a NUL terminator, and unlikely
the expected result.

Use the proper one, strlcpy() instead.

Signed-off-by: Takashi Iwai <tiwai@suse.de>