rtw88: decompose while(1) loop of power sequence polling command

The power polling command is one kind of power sequence commands. It's used
to check hardware situation, and subsequent comamnds will be executed if
hardware is ready. A special case is PCIE must toggle BIT_PFM_WOWL and try
again if first try is failed.

In order to reduce indentation to understand the code easier, move polling
part to a separate function. Then, the 'while (1)...loop' is replaced by
two statements to do first try and retry.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200422034607.28747-5-yhchuang@realtek.com