wifi: rtw89: Remove the redundant else branch in the function rtw89_phy_get_kpath

The assignment of the else and if branches is the same in the "case:
MLO_2_PLUS_0_1RF" branch of the function rtw89_phy_get_kpath, so we
remove it and add comments here to make the code easier to understand.

./drivers/net/wireless/realtek/rtw89/phy.c:6406:2-4: WARNING: possible condition with no effect (if == else).

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=8812
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/20240422072922.50940-1-jiapeng.chong@linux.alibaba.com