drm/msm/shd: correct base connector state at lastclose

For shared display, the base crtc/connector are setup manually in
kernel and is hidden from user. However in lastclose command all
crtc/connector will be closed and base connector's state will be
checked accordingly. Currently when base display is disabled, only
crtc in state is cleared, which causes warning message. This change
will clear the encoder in base connector state to avoid the warning.

Change-Id: I8b8bc741291186c63cc764a45bd5b7e3a27e11c3
Signed-off-by: Xiaowen Wu <wxiaowen@codeaurora.org>