Revert "genetlink: add CAP_NET_ADMIN test for multicast bind"

This reverts commit 30cc13fe.

It does not have a direct commit relation in upstream, and was lovingly
hand-crafted just for the 4.19.y kernel tree with the hope that it would
be useful to someone.

Unfortunately for us, it breaks the Android kernel abi and so, if it is
really needed in the future, must be brought back in an abi-safe way
then.

Bug: 161946584
Change-Id: I12a953b74673556a3b94a0b8bbdc453f3c08db04
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>