rtw89: refine naming of rfk helpers with prefix

Since these macro in rfk helpers are common now, a common naming
should be better. So, apply RTW89_ as prefix to them, and modify
the use correspondly. No logic is changed at all.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220211075953.40421-3-pkshih@realtek.com