msm: ipa: ipa_usb: teth_prot and ttype validation

Add input validation logic for accessing teth_prot and ttype
members.

Change-Id: I05780fb3b09616b7a9cf0c36f71e9f1e5e49f136
CRs-Fixed: 2091803
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>