wifi: rtw89: refine uplink trigger based control mechanism

Rename support_ul_tb_ctrl to waveform_ctrl since we need to do more
trigger based control and the naming could be confusing. Move related
code to leaf function so we make each functions separate and can be
easier to maintain.

Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230929004024.7504-2-pkshih@realtek.com