drm/amdgpu: fix hung reset queue array memory allocation

By design the MES will return an array result that is twice the number
of hung doorbells it can report.

i.e. if up k reported doorbells are supported, then the
second half of the array, also of length k, holds the HQD information
(type/queue/pipe) where queue 1 corresponds to index 0 and k,
queue 2 corresponds to index 1 and k + 1 etc ...

The driver will use the HDQ info to target queue/pipe reset for
hardware scheduled user compute queues.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>