rtlwifi: btcoex: 21a 2ant: Delete several duplicate condition branch codes

The statements of the "if (max_interval == 3)" branch are the same as
those of the "else" branch. Delete them to simplify the code.

No functional change.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210510082237.3315-1-thunder.leizhen@huawei.com