drm/amd/amdgpu: Fix a less than zero check on a uint32_t struct field

Currently the error check from the call to mes_v12_inv_tlb_convert_hub_id
is always false because a uint32_t struct field hub_id is being used to
to perform the less than zero error check. Fix this by using the int
variable ret to perform the check.

Fixes: 87e65052 ("drm/amd/amdgpu : Use the MES INV_TLBS API for tlb invalidation on gfx12")
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>