msm_fb: HDMI: Cleanup of HDMI switch device notifications

HDMI switch device is used to notify userspace components of the
availabilty of a connected HDMI sink. These notification should
only be sent whenever HDMI cable is connected or disconnected.
This patch removes all the redundant notifications.

CRs-Fixed: 412575
Change-Id: Ia5e60690a87569fce5d61a9af75d446648443e9b
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>