wifi: rtw89: mac: correct register of report IMR

The register of report IMR is chip specific, so add a field to strut to
correct them.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220927062611.30484-8-pkshih@realtek.com