wifi: rtw89: refine hardware scan C2H events

Define struct for scan offload C2H events and update each elements'
bitfield. This patch does not change original behavior, just style
conversion and naming changes.

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://msgid.link/20240119081501.25223-3-pkshih@realtek.com