SystemUI: allow to limit the max framerate of built-in screen recorder

Some devices seem to have problems when running the screen recorder at
native resolution @ max fps (I'm looking at you surya). The symptoms may
include severe lagging in the recording or stuff like crashes when
stopping in a landscape orientation. Allow limiting the recorder fps to
fix these issues.

Test: record screen on surya with config_screenRecorderMaxFramerate==90
while screen is running @ 120Hz, observe a smooth video. Stop the
recording while in full screen landscape youtube video, observe no crash

Signed-off-by: Kuba Wojciechowski <nullbytepl@gmail.com>
Change-Id: I361c7ae4bf74f2dd67b86e960f8d2d6ef63f5b8f