cellular: Fix timing problem with network_MobileSuspendResume

Poll to check device power state after suspend-resume. It can take up to
30 seconds for the device state to be updated because of long modem turn
on time.

BUG=chromium:221265
TEST=network_MobileSuspendResume passes on link and lumpy.

Change-Id: I015fe6ee9a4cc6692e338d3303226ff76499d3af
Reviewed-on: https://gerrit.chromium.org/gerrit/49726
Reviewed-by: Thieu Le <thieule@chromium.org>
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
1 file changed