drm/amd/display: Remove register from DCN35 DMCUB diagnostic collection

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Remove register from DCN35 DMCUB diagnostic collection [Why] These registers should not be read from driver and triggering the security violation when DMCUB work times out and diagnostics are collected blocks Z8 entry. [How] Remove the register read from DCN35.