msm_fb: display: exit properly when rotator max session reached

When rotator session reach maximum, it should exit without calling
put_img since no get_img had been called.

CRs-fixed: 466462
Change-Id: I951570227ebd81da6dad19c1b897cde84f8d0451
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>