selftests: fix dependency checker script

This patch fixes inconsistencies in the parsing rules of the levels 1
and 2 of the kselftest_deps.sh.  It was added the levels 4 and 5 to
account for a few edge cases that are present in some tests, also some
minor identation styling have been fixed (s/    /\t/g).

Signed-off-by: Ricardo B. Marliere <rbmarliere@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>