storage::AVREEPROM: Only compile this on AVR

The `AVREEPROM` storage is AVR-specific, and it depends on features and headers
that may not make sense elsewhere. As such, guard it with an `#ifdef`, to only
compile it for AVR-based devices.

Fixes #718.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/driver/storage/AVREEPROM.h

@@ -17,6 +17,8 @@
 
 #pragma once
 
+#ifdef ARDUINO_ARCH_AVR
+
 #include "kaleidoscope/driver/storage/Base.h"
 #include <EEPROM.h>
 
@@ -57,3 +59,5 @@ class AVREEPROM : public kaleidoscope::driver::storage::Base<_StorageProps> {
 }
 }
 }
+
+#endif