wil6210: support FCC board file

Driver already supports China specific board file.
Extend this to support list of countries that follow FCC rules. Upon
reg domain change, use appropriate (default, CN or FCC) board file.

Change-Id: Ia62977fdb1b1da6b985909d7e8dfa239c124e9a0
Signed-off-by: Dedy Lansky <dlansky@codeaurora.org>