msm: mdss: store cont splash flag in fb var struct

Store the continuous splash state in the fb var struct,
so that recovery/other processes can check if the continuous
splash is enabled or not before performing a blank/unblank.

Change-Id: Ieee9a7450c607666c2888df95ed3fc6a0ad286ae
Signed-off-by: Krishna Chaitanya Devarakonda <kdevarak@codeaurora.org>