SystemUI: Fix pink progress animation color in expanded Wi-Fi tile

For some reason, this is applying the completely wrong color.
Following the code, it should show the default defined
accent_device_default_dark color with an alpha of 0.6.

Remove it to avoid the issue.

Test: Turn off Wi-Fi. Expand Wi-Fi quick tile. Observe pink
color on progress anim is gone.

Change-Id: I2510a7cd90abb71e94b7698a7d28581517eb41b4