mwifiex: scan: simplify ternary operators using gnu extension

"x ? x : y" can be simplified as "x ? : y"
https://gcc.gnu.org/onlinedocs/gcc/Conditionals.html#Conditionals



Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>