wil6210: support Talyn specific FW file

FW file name for Talyn device is different from the default name.
This patch searches for Talyn specific FW file name and fallback
to the default FW file in case it is not present.

Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>