qcacmn: Fix dp_internal.h documentation

The kernel-doc script identified a large number of documentation
issues in dp/wifi3.0/dp_internal.h, so fix those issues. In addition,
there are a number of instances where public functions have their
implementation documented instead of having their interface
documented, so duplicate that documentation. The documentation at the
implementation will be removed separately.

Change-Id: I9684f5c2da7edb621a53dfbc5f1f8de2c70d8382
CRs-Fixed: 3373166