Adopt lockscreen shortcut hint from AOSP

In AOSP for icons like Camera, Phone or voice assist it says "Swipe from icon for..."
When adding custom lockscreen shortcuts it currently says "Swipe left/right for..."
It would be better if we have some consistency here.

This patch adopts the AOSP hint for all custom lockscreen shortcuts.

Change-Id: I68222750f07daa64fb0ac42eb903317cfad2bc1c
Signed-off-by: Sebastian Haderecker <sebastian.haderecker@gmail.com>