drm/amdgpu: Fix memory leak in hpd_rx_irq_create_workqueue()

If construction of the array of work queues to handle hpd_rx_irq offload
work fails, we need to unwind. Destroy all the created workqueues and
the allocated memory for the hpd_rx_irq_offload_work_queue struct array.

Fixes: 8e794421 ("drm/amd/display: Fork thread to offload work of hpd_rx_irq")
Signed-off-by: Rafael Mendonca <rafaelmendsr@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>