rtw88: add dump firmware fifo support

Rtw88 currently has a function to dump reserved page section of the
firmware fifo. Reserved page is just part of the firmware fifo, there
are multiple sections in the firmware fifo for different usages, such as
firmware rx fifo and tx fifo.
This commit adds a function to check not only the reserved page section
but also other parts of the firmware fifo. In addition, we need to dump
firmware fifo to dump the debug log message if firmware crashes.

Signed-off-by: Tzu-En Huang <tehuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200925061219.23754-4-tehuang@realtek.com