wifi: rtw89: check path range before using in rtw89_fw_h2c_rf_ps_info()

The variable 'path' from rtw89_phy_get_syn_sel() as index of array could
be 3, but array size is 2. Fortunately, current chip->rf_path_num is
smaller or equal to 2, so it is safe. To prevent mistakes in the future,
add a checking and avoid Coverity warnings.

Addresses-Coverity-ID: linux-next: 1644716 ("Out-of-bounds write")
Addresses-Coverity-ID: linux-next: 1644717 ("Out-of-bounds write")

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250715035259.45061-6-pkshih@realtek.com