Wifi: Replace dual_band with 5GHz band support

As part of the support of the 6GHz band, the concept of dual-band is no
longer valid since we have more than 2 bands supported by Android and
can be checked on the device.

This commit replaces checks on dual-band support with an explicit check
on 5GHz band support.

Bug: 145936758
Bug: 139354972
Test: Manual
Change-Id: Ia118dedb573f61a148764146edf8091ae253a3e2