rtw89: add power_{on/off}_func

New chipset uses individual power_{on/off} functions to replace old power
sequences, because it is hard to represent new complicated flow in a
sequence table.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220307060457.56789-7-pkshih@realtek.com