drm/amdgpu/userq: add a helper to check which IPs are enabled

Add a helper to get a mask of IPs which support user queues.
Use this in the INFO IOCTL to get the IP mask to replace
the current code.

Reviewed-by: Prike Liang <Prike.Liang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>