1. The poison fifo is only used for poison consumption
   requests.
2. Merge reset requests when poison fifo caches multiple
   poison consumption messages

Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>