Input: bfin_rotary - mark suspend and resume code as __maybe_unused

Instead of using #ifdef to guard potentially unused suspend and resume code
let's mark them as __maybe_unused so they still get discarded if they are
not used but we do not get warning. This allows for better compile coverage.

Acked-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>