Rename KGD_MAX_QUEUES to AMDGPU_MAX_QUEUES to conform with
the naming convention followed in amdgpu_gfx.h. No functional
change.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>