ALSA: rawmidi: More constification

Apply const prefix to the static flag info table.

Just for minor optimization and no functional changes.

Link: https://lore.kernel.org/r/20200105144823.29547-42-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/rawmidi.c

@@ -249,7 +249,7 @@ static int assign_substream(struct snd_rawmidi *rmidi, int subdevice,
 {
 	struct snd_rawmidi_substream *substream;
 	struct snd_rawmidi_str *s = &rmidi->streams[stream];
-	static unsigned int info_flags[2] = {
+	static const unsigned int info_flags[2] = {
 		[SNDRV_RAWMIDI_STREAM_OUTPUT] = SNDRV_RAWMIDI_INFO_OUTPUT,
 		[SNDRV_RAWMIDI_STREAM_INPUT] = SNDRV_RAWMIDI_INFO_INPUT,
 	};