In case the device has only touchscreen input device and no keyboard or mouse,
the top level surface is never activated. The behavior differs from a device
which has a keyboard (or gpio-keys, or even uinput-emulated keyboard), where
callchain activate()->weston_view_activate()->weston_seat_set_keyboard_focus()->
weston_keyboard_set_focus()->wl_signal_emit(&keyboard->focus_signal, keyboard)->
handle_keyboard_focus()->weston_desktop_surface_set_activated(..., true); sets
the top level surface as activated. On device with touchscreen, the above is
never called, hence the top level surface is never activated. Add explicit
weston_desktop_surface_set_activated(shsurf->desktop_surface, true); into
activate() to always active the top level surface.

This fixes at least two known issues on such devices:
- Wayland terminal cursor is an empty bar (full bar with keyboard present)
- Chromium dropdown menus are randomly placed (they are placed correctly
  when keyboard is present, because then chromium can find the activated
  top level surface)

Signed-off-by: Marek Vasut <marex@denx.de>