test-definitions: kselftest upgrade to v5.10

[Naresh Kamboju]

If you are not using the test-definitions project to run kselftest,
please ignore this email.

A new run script for kselftest, run_kselftest.sh [1], was created during the
Linux v5.10 release.

This script allows someone to run both individual test cases and sets of
test cases. Accordingly, the test-definitions kselftest script [2] was also
improved to support these upstream changes [1].  Currently this change is in
the test-definitions repository in a separate branch "kselftest". This has been
running in LKFT's CI since November 2020 [3].

The test-definitions kselftest script will stop supporting older versions of
the kselftest run script starting 1st-Feb-2021 from master branch.
OTOH, One have to use test-definitions Tag 2021.01 (will be created) for older
kselftest versions.

We request that any users of test-definitions project start updating your
kselftest sources to version v5.10 and above.

Upstream patch,
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/tools/testing/selftests/run_kselftest.sh?id=5da1918446a1d50d57f2f6062f7fdede0b052473
[2] https://github.com/Linaro/test-definitions/tree/kselftest/automated/linux/kselftest
[3] https://github.com/Linaro/test-definitions/tree/kselftest

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