drm/amd/pm: increase time out value when sending msg to SMU

when do S3 stress, low rate that PowerUpVcn message will get response
more than 1s, so here increase the timeout to 2s

Signed-off-by: charles sun <charles.sun@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>