As made mention of in commit 08c677cb0b43 ("drm/amdgpu: fix
amdgpu_irq_put call trace in gmc_v10_0_hw_fini") and commit 13af556104fa
("drm/amdgpu: fix amdgpu_irq_put call trace in gmc_v11_0_hw_fini"). It
is meaningless to call amdgpu_irq_put() for gmc.ecc_irq. So, remove it
from gmc_v9_0_hw_fini().