Re-apply "CHROMIUM: tests: increase timeout for modem status update"

This CL re-applies the timeout change in CL:280606 to
'plugins/tests/test-fixture.c' after merging with upstream.

BUG=chromium:680751
TEST=`FEATURES=test emerge-$BOARD modemmanager-next`

Change-Id: Ia80c8df5d2c3a7b5acca76158ef87357afecaeab
1 file changed