Revert "Change QWindow::visible when surface visibility in ivi shell changes"

Revert "Change QWindow::visible when surface visibility in ivi shell changes"

This reverts commit d0f95885030e5f425c0423a7a29414a204aaa341.

This is root cause of issue that screen doesn't change
from blank screen after booting.

ivi-surface's visibility must not link to QWindow's visibility
because changing it's visibility to 0 means destroying wayland
surface (--> eglsurface --> ivi-surface) immmediatly.

On the other hand, ivi-surface is created with
visibility == 0. Therefore, creating ivi-surface triggers
self destruction of ivi-surface itself immediately.

And to make matters worse, Qt5.7's hiding(visibility == 0)
window method, wl.attach(nil, 0, 0) was wrong, it cause
unpredictable operation of weston (In our case, it drops some
events between WindowManager and Weston).

For linking ivi-surface's visibility and visibility in QML,
we should consider another method. At least, commit d0f958's
approach is incorrect in Qt5.7 so far.

Change-Id: Ibe90f9dae634aa5cdb3c166caf4db02dfd71965b
Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>