fix(redox-driver-sys): restore redox_syscall alias in io.rs and fix Result type

io.rs uses redox_syscall::dup, ::CallFlags, ::ProcSchemeVerb but was
missing the 'use syscall as redox_syscall' alias (was removed earlier
because cargo check passed locally without it, but actual build needs it).

Also fixed: the non-redox arm of acquire_iopl was using crate::Result
which is a 1-generic type alias; std::result::Result with 2 generics
is what's needed here.

Removed leftover cfg attribute and duplicate use crate::Result.

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

@@ -1,10 +1,11 @@
 #[cfg(all(target_arch = "x86_64", target_os = "redox"))]
 
+use syscall as redox_syscall;
 
 use crate::Result;
 
 #[cfg(all(target_arch = "x86_64", target_os = "redox"))]
-pub fn acquire_iopl() -> Result<()> {
+pub fn acquire_iopl() -> Result<(), crate::DriverError> {
     extern "C" {
         fn redox_cur_thrfd_v0() -> usize;
     }
@@ -20,8 +21,9 @@ pub fn acquire_iopl() -> Result<()> {
 }
 
 #[cfg(all(target_arch = "x86_64", not(target_os = "redox")))]
-pub fn acquire_iopl() -> Result<(), crate::DriverError> {
-    Err(crate::DriverError::Other(String::from(
+pub fn acquire_iopl() -> std::result::Result<(), crate::DriverError> {
+    use crate::DriverError;
+    Err(DriverError::Other(String::from(
         "acquire_iopl: only available on Redox",
     )))
 }
@@ -67,8 +69,3 @@ pub fn inw(port: u16) -> u16 {
 pub fn outw(port: u16, val: u16) {
     unsafe { core::arch::asm!("outw {1:x}, {0:x}", in(reg) val, in(reg) port) };
 }
-
-#[cfg(all(target_arch = "x86_64", target_os = "redox"))]
-
-
-use crate::Result;