drm/amdgpu/display: adjust msleep limit in dp_wait_for_training_aux_rd_interval

Some architectures (e.g., ARM) have relatively low udelay limits.
On most architectures, anything longer than 2000us is not recommended.
Change the check to align with other similar checks in DC.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>