ALSA: hda/ca0132: Use struct_size()

For code simplification and safety, use struct_size() macro for
calculating the dsp_image_seg object size.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_ca0132.c

@@ -2731,7 +2731,7 @@ static bool is_last(const struct dsp_image_seg *p)
 
 static size_t dsp_sizeof(const struct dsp_image_seg *p)
 {
-	return sizeof(*p) + p->count*sizeof(u32);
+	return struct_size(p, data, p->count);
 }
 
 static const struct dsp_image_seg *get_next_seg_ptr(