msm: mdss: add backward compatibility for hardware cursor

Hardware cursor within mdss from mdss v1.5 onwards is
programmed within the SSPP interface. And also, cursors
were expected to be programmed through the overlay interface
by the user. This change adds backward compatibility to cursor
programming and allows it to be programmed through the CURSOR
IOCTL.

Change-Id: Ib4c8401fb2a241f7af3d277efe9b0db364fca70a
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>