ALSA: usb: fcp: Fix hwdep read ops types

The FCP driver defined hwdep read function with ssize_t, but it should
be long due to historical reason.  This caused build errors on 32bit
archs.

Fixes: 46757a3 ("ALSA: FCP: Add Focusrite Control Protocol driver")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://patch.msgid.link/20250120145617.07945574@canb.auug.org.au
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: sfrothwell

sound/usb/fcp.c

@@ -815,13 +815,13 @@ static int fcp_hwdep_ioctl(struct snd_hwdep *hw, struct file *file,
 	/* not reached */
 }
 
-static ssize_t fcp_hwdep_read(struct snd_hwdep *hw, char __user *buf,
-			      ssize_t count, loff_t *offset)
+static long fcp_hwdep_read(struct snd_hwdep *hw, char __user *buf,
+			   long count, loff_t *offset)
 {
 	struct usb_mixer_interface *mixer = hw->private_data;
 	struct fcp_data *private = mixer->private_data;
 	unsigned long flags;
-	ssize_t ret = 0;
+	long ret = 0;
 	u32 event;
 
 	if (count < sizeof(event))