accel/ivpu: Use workqueue for IRQ handling

Convert IRQ bottom half from the thread handler into workqueue.
This increases a stability in rare scenarios where driver on
debugging/hardening kernels processes IRQ too slow and misses
some interrupts due to it.
Workqueue handler also gives a very minor performance increase.

Signed-off-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250107173238.381120-6-maciej.falkowski@linux.intel.com