drm/msm/dsi-staging: avoid out of bounds access of ctrl array

To avoid out of bounds access of ctrl array, an extra check
against maximum possible value is required. This is implemented
using macro display_for_each_ctrl.

Change-Id: I0e74fbf5d4229027ac9f001181992d898ef0c0c7
Signed-off-by: Ritesh Kumar <riteshk@codeaurora.org>