cnss: Add support for FW version 2.0 and 3.0

WLAN driver queries CNSS driver to get the FW files, and FW files are
setup based on the revision ID read from PCI config space. Add support
for version 2.0 and 3.0 FW files.

Change-Id: I753ad5762cfeae97655abc9bc85fa7eaceb5abd1
Signed-off-by: Sameer Thalappil <sameert@codeaurora.org>