Revert "net: add exit_batch_rtnl() method"

This reverts commit fae8bd0b which is
commit fd4f101e 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: I563cda834b80b2d11d7b3259caeb09ee499bce11
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>