fix(redox-driver-sys): use std::result::Result for acquire_iopl and rename unused param

The redox arm of acquire_iopl was using 'crate::Result' which is a
1-generic type alias. Use std::result::Result<(), Error> instead.

Also rename unused 'product' param to '_product' in lookup_hid_quirks.

local/recipes/drivers/redox-driver-sys/source/src/io.rs

@@ -2,10 +2,8 @@
 
 use syscall as redox_syscall;
 
-use crate::Result;
-
 #[cfg(all(target_arch = "x86_64", target_os = "redox"))]
-pub fn acquire_iopl() -> Result<(), crate::DriverError> {
+pub fn acquire_iopl() -> std::result::Result<(), crate::DriverError> {
     extern "C" {
         fn redox_cur_thrfd_v0() -> usize;
     }

local/recipes/drivers/redox-driver-sys/source/src/quirks/mod.rs

@@ -568,6 +568,6 @@ bitflags::bitflags! {
 }
 
 /// Look up USB HID quirks for a vendor/product pair.
-pub fn lookup_hid_quirks(vendor: u16, product: u16) -> HidQuirkFlags {
+pub fn lookup_hid_quirks(vendor: u16, _product: u16) -> HidQuirkFlags {
     HidQuirkFlags::empty()
 }