Docs: Move debug authentication documentation

The documentation for the debug authentication configuration was
originally placed to the integration guide of the platform service,
to which it is completely unrelated. Move the text to the documentation
of the platform folder.

Change-Id: I58f5c121052f0aba2c014b00d983faff739ce2fe
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
2 files changed