msm: mdss: restore secure config after toggling gdsc

After coming out of mdss power collapse, need scm call to restore secure
configuration and allow access to protected hardware registers.

Change-Id: Ie1294e37674bb8e9065e438e1c1a2deee80d49e0
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>