For handling 6Ghz RNR related operations create
new file.
The helper functions are used to update and maintain
global context of lower band vdev count, 6Ghz vdev
count and pointer to 6Ghz pdev.
This will provide global access to 6Ghz pdev and
avoid finding this pdev through iterations over
SoC and Pdevs.
Finding lower band vdev count can be tricky as
it involves iteration over SoC, Pdev and Vdev.
Keeping global counter optimizes the approach to
access without multiple iterations.
Change-Id: Ic9782e517d8a87d4806b93dd4779cd54366316cb
6bca4d3976