net: rmnet_data: Fix comments on code review

- Remove redundant checks in tx / rx fixup.
- Remove debug aggregation counter
- Remove unused recycle handler
- Add CAP_NET_ADMIN checks for set IOCTLs
- Simplify the packet deliver code

CRs-Fixed: 2111801
Change-Id: I14c02462c27b319f7517caa178f25a8efa22abeb
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>