qcacmn: Add support to send twt feature capability

Currently there is no support to send twt capability to
user space.
Add Support to advertise twt capability to user space using
vendor flag QCA_WLAN_VENDOR_FEATURE_TWT when get capability
vendor command is invoked.

Change-Id: I9d6d3dc975485a5d1ad38d4f7c2830b05619a14b
CRs-fixed: 2424356