drm/amd/display: Extend AUX timeout for DP initial reads

[WHY]
DP LL Compliance tests require that the first DPCD transactions after a
hotplug have a timeout interval of 3.2 ms.  In cases where LTTPR is
disabled, this means that the first reads from DP_SET_POWER and DP_DPCD_REV must have an extended
timeout.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>