HID: hid-prodikeys: remove unused struct pcmidi_snd members

struct pcmidi_snd contains two unused members: out_substream and
out_active. They were added along the driver in commit 3a370ca1
(HID: Prodikeys PC-MIDI HID Driver), but not used.

Drop them.

Found by https://github.com/jirislaby/clang-struct.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

drivers/hid/hid-prodikeys.c

@@ -66,9 +66,7 @@ struct pcmidi_snd {
 	struct snd_card			*card;
 	struct snd_rawmidi		*rwmidi;
 	struct snd_rawmidi_substream	*in_substream;
-	struct snd_rawmidi_substream	*out_substream;
 	unsigned long			in_triggered;
-	unsigned long			out_active;
 };
 
 #define PK_QUIRK_NOGET	0x00010000