msm: kgsl: Do not decrease the KGSL open count

Do not reduce the open count in kgsl_close_device to
keep from powering down the GPU.

CRs-Fixed: 2017390
Change-Id: Ibfef14b409f42aa54cc3ce1738793c36ff1fac70
Signed-off-by: Shrenuj Bansal <shrenujb@codeaurora.org>
Signed-off-by: Kyle Piefer <kpiefer@codeaurora.org>