wifi: rtlwifi: remove unreachable code in rtl92d_dm_check_edca_turbo()

Since '!(0x5ea42b & 0xffff0000)' is always false, remove unreachable
block in 'rtl92d_dm_check_edca_turbo()' and convert EDCA limits to
constant variables. Compile tested only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231003043318.11370-1-dmantipov@yandex.ru