drm/amdgpu: RAS emergency restart logic refine

If we are in RAS triggered situation and
BACO isn't support, emergency restart is needed,
and this code is only needed for some specific
cases(vega20 with given smu fw version).

After we add smu mode1 reset for sienna cichlid, we
need to share AMD_RESET_METHOD_MODE1 with psp mode1 reset,
so in amdgpu_device_gpu_recover, we need differentiate
which mode1 reset we are using, then decide if it's
a full reset and then decide if emergency restart is needed,
the logic will become much more complex.

After discussion with Hawking, move emergency restart logic
to an independent function.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Wenhui Sheng <Wenhui.Sheng@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>