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.

Change-Id: I85308cc592e29ea44f4adc94b8d35444a7041ed3
Signed-off-by: Maya Erez <merez@codeaurora.org>