fw/rt_config: Add unlock_screen config option in runtime_parameters

Introduce 'unlock_screen' option in order to help in automating Android
tests by unlocking device screen automatically. Surely this works only
if no passcode is set.

'unlock_screen' option implicitly requires turning on the screen. IOW,
it will override value of 'screen_on' option.

'diagonal', 'vertical' and 'horizontal' are valid values for
'unlock_screen' option as of now.

Note that this patch depends on
https://github.com/ARM-software/devlib/pull/659 in devlib repo.

Signed-off-by: Metin Kaya <metin.kaya@arm.com>

doc/source/user_information/user_reference/runtime_parameters.rst

@@ -33,6 +33,7 @@ states.
                   iterations: 1
                   runtime_parameters:
                         screen_on: false
+                        unlock_screen: 'vertical'
                 - name: benchmarkpi
                   iterations: 1
         sections:
@@ -208,6 +209,13 @@ Android Specific Runtime Parameters
 :screen_on: A ``boolean`` to specify whether the devices screen should be
     turned on. Defaults to ``True``.
 
+:unlock_screen: A ``String`` to specify how the devices screen should be
+    unlocked. Unlocking screen is disabled by default. ``vertical``, ``diagonal``
+    and ``horizontal`` are the supported values (see :meth:`devlib.AndroidTarget.swipe_to_unlock`).
+    Note that unlocking succeeds when no passcode is set. Since unlocking screen
+    requires turning on the screen, this option overrides value of ``screen_on``
+    option.
+
 .. _setting-sysfiles:
 
 Setting Sysfiles