msm: kgsl: Only free interrupts if they have been set

During gmu_remove, we should not unconditionally free
the HFI and GMU interrupts in case probe failed early.

CRs-Fixed: 2017390
Change-Id: Ia3d9deda8937a4e23a84019757190fa57c1c72ee
Signed-off-by: Kyle Piefer <kpiefer@codeaurora.org>