Revert "drm/amdgpu: Configure doorbell to maximum slots"

This reverts commit 78ad5cdd.
This commit breaks dpm and suspend/resume on CZ.

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -3135,7 +3135,7 @@ static int gfx_v8_0_cp_compute_resume(struct amdgpu_device *adev)
 				WREG32(mmCP_MEC_DOORBELL_RANGE_LOWER,
 				       AMDGPU_DOORBELL_KIQ << 2);
 				WREG32(mmCP_MEC_DOORBELL_RANGE_UPPER,
-						0x7FFFF << 2);
+				       AMDGPU_DOORBELL_MEC_RING7 << 2);
 			}
 			tmp = RREG32(mmCP_HQD_PQ_DOORBELL_CONTROL);
 			tmp = REG_SET_FIELD(tmp, CP_HQD_PQ_DOORBELL_CONTROL,