IH ring1 is used to process GPU retry fault, overflow is enabled to
drain retry fault because we want receive other interrupts while
handling retry fault to recover range. There is no overflow flag set
when wptr pass rptr. Use timestamp of rptr and wptr to handle overflow
and drain retry fault.

If fault timestamp goes backward, the fault is filtered and should not
be processed. Drain fault is finished if processed_timestamp is equal to
or larger than checkpoint timestamp.

Add amdgpu_ih_functions interface decode_iv_ts for different chips to
get timestamp from IV entry with different iv size and timestamp offset.
amdgpu_ih_decode_iv_ts_helper is used for vega10, vega20, navi10.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>