selftests/damon: Add executable permission to test scripts

When running the test for the damon subsystem, there are a lot of
warnings because test scripts do not have executable permission,
for example:

Warning: file debugfs_attrs.sh is not executable
Warning: file debugfs_schemes.sh is not executable
Warning: file debugfs_target_ids.sh is not executable
...

This patch adds executable permission to test scripts to eliminate
these warnings.

Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/damon: split test cases

Currently, the single test program, debugfs.sh, contains all test cases
for DAMON. When one of the cases fails, finding which case is failed
from the test log is not so easy, and all remaining tests will be
skipped. To improve the situation, this commit splits the single
program into small test programs having their own names.

Link: https://lkml.kernel.org/r/20211201150440.1088-12-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>