rtw88: extract: export symbols about pci interface

In the current design, chip entry points are built into
the pci module. That makes the pci module depend on chips.
According to dependence, once the pci module is loaded,
kernel will load chip functionalities, including those that
may not be currently used.

We plan to split chip entry points from the pci module.
Thence we export pci symbols that will be used in chip
entry point modules.

Signed-off-by: Zong-Zhe Yang <kevin_yang@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/20200515052327.31874-3-yhchuang@realtek.com