drm/amd/display: Add 'replay' NULL check in 'edp_set_replay_allow_active()'

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Add 'replay' NULL check in 'edp_set_replay_allow_active()'

In the first if statement, we're checking if 'replay' is NULL. But in
the second if statement, we're not checking if 'replay' is NULL again
before calling replay->funcs->replay_set_power_opt().

if (replay == NULL && force_static)
return false;

...

if (link->replay_settings.replay_feature_enabled &&
replay->funcs->replay_set_power_opt) {
replay->funcs->replay_set_power_opt(replay, *power_opts, panel_inst);
link->replay_settings.replay_power_opt_active = *power_opts;
}

If 'replay' is NULL, this will cause a null pointer dereference.

Fixes the below found by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_edp_panel_control.c:895 edp_set_replay_allow_active() error: we previously assumed 'replay' could be null (see line 887)