Fix variable name

Author: bugadani

espflash/src/interface.rs

@@ -29,7 +29,7 @@ pub struct Interface {
 
 #[cfg(feature = "raspberry")]
 fn write_gpio(gpio: &mut OutputPin, level: bool) {
-    if pin_state {
+    if level {
         gpio.set_high();
     } else {
         gpio.set_low();