arecordmidi2: Fix truncated text in meta data text handling

The current code didn't proceed the text position buffer and the text
was always truncated in 12 bytes.  Let's fix it.

Fixes: 74daf3a93a ("arecordmidi2: Add options to put meta data texts")
Signed-off-by: Takashi Iwai <tiwai@suse.de>

seq/aplaymidi2/arecordmidi2.c

@@ -416,6 +416,7 @@ static void write_metadata(FILE *file, unsigned int type, const char *text)
 
 		fwrite(d.raw, 4, 4, file);
 		len -= size;
+		text += size;
 		format = SND_UMP_FLEX_DATA_MSG_FORMAT_CONTINUE;
 	}
 }