qcacmn: Fix interop VHT vendor IE parse error

Currently when parsing interop VHT vendor IE, it will have OOB
read when only VHT cap IE is present.

Try to read VHT op IE only when it is present.

Change-Id: Id1919a0ed1df56ecef54d6cb663c10cbcae5065f
CRs-Fixed: 2453071
1 file changed