wifi: rtw88: access chip_info by const pointer

Since chip_info has became const table, we must access them via const
pointer to avoid invalid writing.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220727065232.28510-1-pkshih@realtek.com