This moves the rtl8723a code into it's own file. This is purely a code
moving exercise, no code changes.

This device specific file is a lot smaller since the gen1 chips
(8723a, 8188c, 8188r, 8192c) share a lot more common code than the
gen2 chips.
Signed-off-by: NJes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>