drm/amdgpu: adjust default display clock

Increase the default display clock on newer asics to
accomodate some high res modes with really high refresh
rates.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=93826


Acked-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org