wifi: rtw89: use u32_get_bits to access C2H content of PHY capability

The definitions of bit fields in structure will be wrong in big-endian
platform, so use u32_get_bits() to access them.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220908074140.39776-2-pkshih@realtek.com