Revert "bpf: Fix helper writes to read-only maps"

This reverts commit 988e55ab which is
commit 32556ce9 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: Ibd0d120be102c66e57d9d418a5ccd02178022713
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>