digial_io: gpio: make find_line match hardware.rs behaviour

The find_line in hardware.rs returns an Option<_> match that in
demo_mode.rs and test.rs.

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>

Author: hnez

src/digital_io/gpio/demo_mode.rs

@@ -81,8 +81,8 @@ impl FindDecoy {
     }
 }
 
-pub fn find_line(name: &str) -> Result<FindDecoy> {
-    Ok(FindDecoy {
+pub fn find_line(name: &str) -> Option<FindDecoy> {
+    Some(FindDecoy {
         name: name.to_string(),
     })
 }

src/digital_io/gpio/test.rs

@@ -88,7 +88,7 @@ impl FindDecoy {
     }
 }
 
-pub fn find_line(name: &str) -> Result<FindDecoy> {
+pub fn find_line(name: &str) -> Option<FindDecoy> {
     let val = {
         let mut lines = block_on(LINES.lock());
 
@@ -101,7 +101,7 @@ pub fn find_line(name: &str) -> Result<FindDecoy> {
         }
     };
 
-    Ok(FindDecoy {
+    Some(FindDecoy {
         name: name.to_string(),
         val,
     })