ALSA: hda: Improve local variable data type in snd_hda_get_num_devices()

ALSA: hda: Improve local variable data type in snd_hda_get_num_devices()

Use 'int' instead of 'unsigned int' because the local variable 'parm'
can be negative.

While an unsigned integer is harmless in practice due to the implicit
type conversion, it's safer and more idiomatic to use a signed integer
to properly check for -1.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20250813103418.164110-2-thorsten.blum@linux.dev
Signed-off-by: Takashi Iwai <tiwai@suse.de>