rust: revocable: support fallible PinInit types

rust: revocable: support fallible PinInit types

Currently, Revocable::new() only supports infallible PinInit
implementations, i.e. impl PinInit<T, Infallible>.

This has been sufficient so far, since users such as Devres do not
support fallibility.

Since this is about to change, make Revocable::new() generic over the
error type E.

Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20250626200054.243480-2-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>