selftests/bpf: Alphabetize DENYLISTs

The DENYLIST and DENYLIST.s390x files are used to specify testcases
which should not be run on CI. Currently, testcases are appended to the
end of these files as needed. This can make it a pain to resolve merge
conflicts. This patch alphabetizes the DENYLIST files to ease this
burden.

Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Daniel Müller <deso@posteo.net>
Link: https://lore.kernel.org/r/20221011165255.774014-1-void@manifault.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>