Revert "genetlink: add CAP_NET_ADMIN test for multicast bind"

This reverts commit 015870c1 which does
not have a direct relation to an upstream commit.

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: I8ddc8a86b47a9560115ccb83fc50d522436d0b3b
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>