msm: ipa: Use correct VLAN header size in partial headers

Fix IPA offload sub-system to use correct VLAN ethernet header size
while registering partial headers with IPA driver.

CRs-Fixed: 2496455
Change-Id: Iaf85a3d049c8b99062f9b242c705cb348bdea826
Signed-off-by: Jinesh K. Jayakumar <jineshk@codeaurora.org>