Add focus indicator only when attaching physicalkeyboard

Add focus indicator only when attaching physicalkeyboard

Add focus indicator only when attaching physicalkeyboard.

When user wants to preset focus actor before physicalkeyboard is attached,
they can call SetCurrentFocus().

Before this patch, it always displays focus indicator whether
pyhisicalkeyboard is attached or not.

Now, if pyhisicalkeyboard is not attached, SetCurrentFocus() dosen't
add focus indicator to focus actor.

Change-Id: Iab67127a1079b724f68ab44683684cc06360d82c
Signed-off-by: minho.sun <minho.sun@samsung.com>