drm/amdkfd: Delete alloc_format field from map_queue struct

Alloc format was never really supported by MEC FW. FW always
does one per pipe allocation.

Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>