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

This reverts commit a2c8dc7e 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: Ibf46c486bc4c7c5fd04bf1955260691417462edb
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>