drm/msm/dp: clear panel data on notification failure

Clear the panel data on notification failure to ensure
that all data structures are reset and previously
allocated memory, e.g. the EDID buffer, is freed.

CRs-Fixed: 2332446
Change-Id: I4b3cd7ea3e54fc1d364e27b16ec20c1634330d6e
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>