rtw88: extract: export symbols used in chip functionalities

In the current design, various chip functions and tables
are built into rtw88 core. That causes kernel to load its
functionalities even if a chip isn't currently used. We
plan to make each chip's functionalities a separate
kernel module to reduce rtw88 core. And kernel will be
able to load the necessary.

Before extracting chip functionalities, we export symbols
inside rtw88 core which will be used in chip 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/20200515052327.31874-2-yhchuang@realtek.com