drm/radeon: clear needs_reset flag if IB test fails

If the IB test fails we don't want to reset the card over
and over again, just accept that it isn't working.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=76501



Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org