accel/ivpu: Limit number of maximum contexts and doorbells per user

accel/ivpu: Limit number of maximum contexts and doorbells per user

Implement per-user resource limits to prevent resource exhaustion.

Root users can allocate all available contexts (128) and doorbells
(255), while non-root users are limited to half of the available
resources (64 contexts and 127 doorbells respectively).

This prevents scenarios where a single user could monopolize NPU
resources and starve other users on multi-user systems.

Change doorbell ID and command queue ID allocation errors to debug
messages as those are user triggered.

Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Lizhi Hou <lizhi.hou@amd.com>
Signed-off-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Link: https://patch.msgid.link/20260302202207.469442-1-maciej.falkowski@linux.intel.com