msm_fb: display: Fix incorrect goto call

During the probe for writeback panel, for MDP hardware versions
earlier than 4.3 an incorrect goto call un registers the bus scale handle
that primary panel uses. This is causing the boot failures because the
primary panel turn on sequence triggers the bus scale update request on
already unregistered handle.

Change-Id: Ie604b0ba5606d9664d2aeff28b8bea131965de61
Signed-off-by: Rajesh Sastrula <vrajesh@codeaurora.org>