Revert "bpftool: Mount bpffs when pinmaps path not under the bpffs"

This reverts commit 65dd9cba which is
commit da5f8fd1 upstream.

It breaks the build, so should be dropped.

Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Link: https://lore.kernel.org/r/ZrSe8gZ_GyFv1knq@eldamar.lan


Cc: Tao Chen <chen.dylane@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Quentin Monnet <qmo@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>