drm/amd/display: change SMU repsonse timeout to 2s.

[Why]
there is some garbage showing up during reboot test.
Reason:
SMU might handle display driver msg defered and driver will send
next msg to SMU after 10ms timeout, once SMU FW handle previous msg,
parameters are changed to next one, which result in a wrong value be programmed.

[How]
Extend timeout to 2s so SMU will have enough time to handle driver msg.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Bindu Ramamurthy <bindu.r@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>