Revert "drm/radeon: Fix EEH during kexec"

This reverts commit 6f7fe9a9.

This breaks some boards.  Maybe just enable this on PPC for
now?

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=205147


Signed-off-by: Alex Deucher <alexander.deucher@amd.com>