Implement Into<Infallible> when spi::DeviceError is infallible

This improves integration with infallible SPI device driver APIs that constrain the SPI device error type
to Into<Infallible>, allowing types such as DeviceError<Infallible, Infallible> to be used.

Author: t-wallet

embedded-hal-bus/src/spi/mod.rs

@@ -1,5 +1,6 @@
 //! `SpiDevice` implementations.
 
+use core::convert::Infallible;
 use core::fmt::{self, Debug, Display, Formatter};
 use embedded_hal::spi::{Error, ErrorKind};
 
@@ -63,6 +64,15 @@ where
     }
 }
 
+impl From<DeviceError<Infallible, Infallible>> for Infallible {
+    fn from(value: DeviceError<Infallible, Infallible>) -> Self {
+        match value {
+            DeviceError::Spi(e) => e,
+            DeviceError::Cs(e) => e,
+        }
+    }
+}
+
 /// Dummy [`DelayNs`](embedded_hal::delay::DelayNs) implementation that panics on use.
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
 #[cfg_attr(feature = "defmt-03", derive(defmt::Format))]