Implement parsing of the CONFIG_LSM kconfig option

[a13xp0p0v]

The CONFIG_LSM kconfig option contains a list of LSM modules loaded by the kernel.
Let's create a simple mechanism for checking that it contains the needed LSM module.

The checking rule might look like this:

l += [KconfigCheck('self_protection', 'kspp', 'LSM', '*lockdown*')]

Here '*lockdown*' means that lockdown is in the comma-separated list.