ALSA: control: remove compilation warning on 32-bit

This was introduced by 'ALSA: control: add support for ENUMERATED user
space controls' which adds a u64 variable that gets cast to a pointer:

sound/core/control.c: In function 'snd_ctl_elem_init_enum_names':
sound/core/control.c:1089: warning: cast to pointer from integer of different size

Cast to uintptr_t before casting to pointer to avoid the warning.
Signed-off-by: NOlof Johansson <olof@lixom.net>
[cl: replace long with uintptr_t]
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/core/control.c

@@ -1081,12 +1081,12 @@ static int snd_ctl_elem_init_enum_names(struct user_element *ue)
 	char *names, *p;
 	size_t buf_len, name_len;
 	unsigned int i;
+	const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
 
 	if (ue->info.value.enumerated.names_length > 64 * 1024)
 		return -EINVAL;
 
-	names = memdup_user(
-		(const void __user *)ue->info.value.enumerated.names_ptr,
+	names = memdup_user((const void __user *)user_ptrval,
 		ue->info.value.enumerated.names_length);
 	if (IS_ERR(names))
 		return PTR_ERR(names);