Revert "drm/amd: Disable S/G for APUs when 64GB or more host memory"

commit 169ed4ec upstream.

This reverts commit 70e64c4d.

Since, we now have an actual fix for this issue, we can get rid of this
workaround as it can cause pin failures if enough VRAM isn't carved out
by the BIOS.

Cc: stable@vger.kernel.org # 6.1+
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>