Revert "i3c: Make i3c_master_unregister() return void"

This reverts commit 87e0f28e which is
commit 0f74f8b6 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ia86a905c65bddaf79dc1e8fffc0609cb2b5b115c
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>