drm/amd/display: fix missing .is_two_pixels_per_container

Starting from 6.11, AMDGPU driver, while being loaded with amdgpu.dc=1,
due to lack of .is_two_pixels_per_container function in dce60_tg_funcs,
causes a NULL pointer dereference on PCs with old GPUs, such as R9 280X.

So this fix adds missing .is_two_pixels_per_container to dce60_tg_funcs.

Reported-by: Rosen Penev <rosenp@gmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3942
Fixes: e6a901a ("drm/amd/display: use even ODM slice width for two pixels per container")
Signed-off-by: Aliaksei Urbanski <aliaksei.urbanski@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit bd4b125)
Cc: stable@vger.kernel.org

Author: Jamim

drivers/gpu/drm/amd/display/dc/dce60/dce60_timing_generator.c

@@ -239,6 +239,7 @@ static const struct timing_generator_funcs dce60_tg_funcs = {
 				dce60_timing_generator_enable_advanced_request,
 		.configure_crc = dce60_configure_crc,
 		.get_crc = dce110_get_crc,
+		.is_two_pixels_per_container = dce110_is_two_pixels_per_container,
 };
 
 void dce60_timing_generator_construct(