msm: mdss: fix cursor alloc and setup

Each pipe holds a list with the addresses to the planes
allocated for each pipe. Current code was missing to
populate this list for the cursor and update the global
list with the correct index for the cursor allocated.
This change fixes this issue by populating the list
and updating the global cursors list.

Change-Id: Ib5bdfd5a93802c05643b74a6ebf396d2d9308365
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>