SystemUI: VolumeDialog: Change bg tint for inactive rows

The secondary accent in light mode does not have a good contrast
to the previously white icon.

Previously: https://imgur.com/a/XHpDHDJ
Now: https://imgur.com/a/QCk3QwC



Change-Id: Ib61ad4803e0e3c6cc9163408137c7a16742922b6
Signed-off-by: Mohammad Hasan Keramat J <ikeramat@protonmail.com>