rtlwifi: btcoex: 23b 1ant: fix duplicated code for different branches

Refactor code in order to avoid identical code for different branches.

This issue was detected with the help of Coccinelle.

Addresses-Coverity-ID: 1415177
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>