accel/habanalabs: fix gaudi2_get_tpc_idle_status() return

The gaudi2_get_tpc_idle_status() function returned the incorrect variable
so it always returned true.

Fixes: d85f0531 ("accel/habanalabs: break is_idle function into per-engine sub-routines")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>