rtw88: remove redundant flag check helper function

These helper functions seems useless. And in some cases
we want to use test_and_[set/clear]_bit, these helpers
will make the code more complicated. So remove them.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>